Extend `localopts' with attributes: [scope], call, call-fixate..

[s-mailx.git] / nail.1

.\"@ nail.1 - S-nail(1) reference manual.
.\"
.\" Copyright (c) 2000-2008 Gunnar Ritter, Freiburg i. Br., Germany.
.\" Copyright (c) 2012 - 2017 Steffen (Daode) Nurpmeso <steffen@sdaoden.eu>.
.\"
.\" Copyright (c) 1980, 1990, 1993
.\"      The Regents of the University of California.  All rights reserved.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions
.\" are met:
.\" 1. Redistributions of source code must retain the above copyright
.\"    notice, this list of conditions and the following disclaimer.
.\" 2. Redistributions in binary form must reproduce the above copyright
.\"    notice, this list of conditions and the following disclaimer in the
.\"    documentation and/or other materials provided with the distribution.
.\" 3. Neither the name of the University nor the names of its contributors
.\"    may be used to endorse or promote products derived from this software
.\"    without specific prior written permission.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
.\" ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
.\" SUCH DAMAGE.
.\"
.\"--MKREL-START--
.\"@ S-nail(1): v14.9.0 / 2017-07-16
.Dd July 16, 2017
.ds VV \\%v14.9.0
.\"--MKREL-END--
.\"--MKMAN-START--
.ds UU \\%S-NAIL
.ds UA \\%S-nail
.ds uA \\%s-nail
.ds UR \\%s-nail.rc
.\"--MKMAN-END--
.\" --BEGINSTRIP--
.\"
.\" If not ~/.mailrc, it breaks POSIX compatibility.  And adjust main.c.
.ds ur \\%~/.mailrc
.ds OB [Obsolete]
.ds OP [Option]
.ds IN [v15-compat]
.ds OU [no v15-compat]
.ds ID [v15 behaviour may differ]
.ds NQ [Only new quoting rules]
.ds BO (Boolean)
.ds RO (Read-only)
.
.Dt "\*(UU" 1
.Os
.Mx -enable
.
.
.Sh NAME
.Nm \*(UA \%[\*(VV]
.Nd send and receive Internet mail
.
.
.\" .Sh SYNOPSIS {{{
.Sh SYNOPSIS
.
.\" Keep in SYNC: ./nail.1:"SYNOPSIS, main()
.Nm \*(uA
.Fl h | Fl Fl help
.Pp
.Nm \*(uA
.Bk -words
.Op Fl BdEFinv~#
.Op Fl \&: Ar spec
.Op Fl A Ar account
.Op : Ns Fl a Ar attachment Ns \&:
.Op : Ns Fl b Ar bcc-addr Ns \&:
.Op : Ns Fl c Ar cc-addr Ns \&:
.Op Fl M Ar type | Fl m Ar file | Fl q Ar file | Fl t
.Op Fl r Ar from-addr
.Oo : Ns
.Fl S Ar var Ns Op Ns = Ns Ar value Ns
.Pf \&: Oc
.Op Fl s Ar subject
.Op : Ns Fl X Ar cmd Ns \&:
.Op Fl \&.
.Pf : Ar to-addr Ns \&:
.Op Fl Fl \~ Ns : Ns Ar mta-option Ns \&:
.Ek
.Pp
.Nm \*(uA
.Bk -words
.Op Fl BdEeHiNnRv~#
.Op Fl \&: Ar spec
.Op Fl A Ar account
.Op Fl L Ar spec
.Op Fl r Ar from-addr
.Oo : Ns
.Fl S Ar var Ns Op Ns = Ns Ar value Ns
.Pf \&: Oc
.Op Fl u Ar user
.Op : Ns Fl X Ar cmd Ns \&:
.Op Fl Fl \~ Ns : Ns Ar mta-option Ns \&:
.Ek
.Nm \*(uA
.Bk -words
.Op Fl BdEeHiNnRv~#
.Op Fl \&: Ar spec
.Op Fl A Ar account
.Fl f
.Op Fl L Ar spec
.Op Fl r Ar from-addr
.Oo : Ns
.Fl S Ar var Ns Op Ns = Ns Ar value Ns
.Pf \&: Oc
.Op : Ns Fl X Ar cmd Ns \&:
.Op Ar file
.Op Fl Fl \~ Ns : Ns Ar mta-option Ns \&:
.Ek
.
.\" }}}
.
.
.Mx -toc -tree html pdf ps xhtml
.
.
.\" .Sh DESCRIPTION {{{
.Sh DESCRIPTION
.
.Bd -filled -compact -offset indent
.Sy Compatibility note:
S-nail (\*(UA) will wrap up into \%S-mailx in v15.0 (circa 2019).
Backward incompatibility has to be expected \(en
.Sx COMMANDS
will use
.Sx "Shell-style argument quoting"
rules, for example, and shell metacharacters will become meaningful.
New and old behaviour is flagged \*(IN and \*(OU, and setting
.Va v15-compat ,
one of the many
.Sx "INTERNAL VARIABLES" ,
will choose new behaviour when applicable.
\*(OB flags what will vanish, and enabling
.Fl d
or
.Fl v
enables obsoletion warnings.
.Ed
.
.Pp
\*(UA provides a simple and friendly environment for sending and
receiving mail.
It is intended to provide the functionality of the POSIX
.Xr mailx 1
command, but is MIME capable and optionally offers extensions for
line editing, S/MIME, SMTP and POP3, among others.
\*(UA divides incoming mail into its constituent messages and allows
the user to deal with them in any order.
It offers many
.Sx COMMANDS
and
.Sx "INTERNAL VARIABLES"
for manipulating messages and sending mail.
It provides the user simple editing capabilities to ease the composition
of outgoing messages, and increasingly powerful and reliable
non-interactive scripting capabilities.
.
.\" .Ss "Options" {{{
.Ss "Options"
.
.Bl -tag -width ".It Fl BaNg"
.Mx
.It Fl \&: Ar spec
Explicitly control which of the
.Sx "Resource files"
shall be loaded: if the letter
.Ql s
is (case-insensitively) part of the
.Ar spec
then the system wide
.Pa \*(UR
is loaded, likewise the letter
.Ql u
controls loading of the user's personal
.Pa \*(ur
file, whereas the letters
.Ql -
and
.Ql /
explicitly forbid loading of any resource files.
This option should be used by scripts: to avoid environmental noise they
should
.Dq detach
from any configuration files and create a script-local environment,
explicitly setting any of the desired
.Sx "INTERNAL VARIABLES"
via
.Fl S .
This option overrides
.Fl n .
.
.Mx
.It Fl A Ar account
Executes an
.Ic account
command for the given user email
.Ar account
after program startup is complete (all resource files are loaded, any
.Fl S
setting is being established; only
.Fl X
commands have not been evaluated yet).
Being a special incarnation of
.Ic define Ns d
macros for the purpose of bundling longer-lived
.Ic set Ns
tings, activating such an email account also switches to the accounts
.Mx -sx
.Sx "primary system mailbox"
(most likely the
.Va inbox ) .
.
.Mx
.It Fl a Ar file Ns Op Ar =input-charset Ns Op Ar #output-charset
Attach
.Ar file
to the message (for compose mode opportunities refer to
.Ic ~@
and
.Ic ~^ ) .
.Sx "Filename transformations"
(also see
.Ic file )
will be performed, but shell word expansion is restricted to the tilde
.Ql ~ .
Shall
.Ar file
not be accessible but contain a
.Ql =
character, then anything before the
.Ql =
will be used as the filename, anything thereafter as a character set
specification.
.Pp
If an input character set is specified,
.Mx -ix "character set specification"
but no output character set, then the given input character set is fixed
as-is, and no conversion will be applied;
giving the empty string or the special string hyphen-minus
.Ql -
will be treated as if
.Va ttycharset
has been specified (the default).
.Pp
If an output character set has also been given then the conversion will
be performed exactly as specified and on-the-fly, not considering the
file's type and content.
As an exception, if the output character set is specified as the empty
string or hyphen-minus
.Ql - ,
then the default conversion algorithm (see
.Sx "Character sets" )
is applied (therefore no conversion is performed on-the-fly,
.Ar file
will be MIME-classified and its contents will be inspected first) \(em
without support for character set conversions
.Pf ( Va features
does not include the term
.Ql +iconv )
only this argument is supported.
.
.It Fl B
(\*(OB: \*(UA will always use line-buffered output, to gain
line-buffered input even in batch mode enable batch mode via
.Fl # . )
.
.Mx
.It Fl b Ar addr
Send a blind carbon copy to
.Ar addr Ns
ess, if the
.Ic set Ns
ting of
.Va expandaddr ,
one of the
.Sx "INTERNAL VARIABLES" ,
allows.
The option may be used multiple times.
Also see the section
.Sx "On sending mail, and non-interactive mode" .
.
.Mx
.It Fl c Ar addr
Send carbon copies to the given receiver, if so allowed by
.Va expandaddr .
May be used multiple times.
.
.Mx
.It Fl d
.Ic set
the internal variable
.Va debug
which enables debug messages and disables message delivery,
among others; effectively turns almost any operation into a dry-run.
.
.Mx
.It Fl E
.Ic set
.Va skipemptybody
and thus discard messages with an empty message part body.
This command line option is \*(OB.
.
.Mx
.It Fl e
Just check if mail is present (in the system
.Va inbox
or the one specified via
.Fl f ) :
if yes, return an exit status of zero, a non-zero value otherwise.
To restrict the set of mails to consider in this evaluation a message
specification can be added with the option
.Fl L .
.
.Mx
.It Fl F
Save the message to send in a file named after the local part of the
first recipient's address (instead of in
.Va record Ns ).
.
.Mx
.It Fl f
Read in the contents of the user's
.Mx -sx
.Sx "secondary mailbox"
.Ev MBOX
(or the specified file) for processing;
when \*(UA is quit, it writes undeleted messages back to this file
(but be aware of the
.Va hold
option).
The optional
.Ar file
argument will undergo some special
.Sx "Filename transformations"
(also see
.Ic file ) .
Note that
.Ar file
is not an argument to the flag
.Fl \&\&f ,
but is instead taken from the command line after option processing has
been completed.
In order to use a
.Ar file
that starts with a hyphen-minus, prefix with a relative path, as in
.Ql ./-hyphenbox.mbox .
.
.Mx
.It Fl H
Display a summary of
.Ic headers
and exit; a configurable summary view is available via the
.Fl L
option.
.
.Mx
.It Fl h
Show a short usage summary.
.
.Mx
.It Fl i
.Ic set
.Va ignore
to ignore tty interrupt signals.
.
.Mx
.It Fl L Ar spec
Display a summary of
.Ic headers
of all messages that match the given
.Ar spec ,
then exit.
See the section
.Sx "Specifying messages"
for the format of
.Ar spec .
If the
.Fl e
option has been given in addition no header summary is produced,
but \*(UA will instead indicate via its exit status whether
.Ar spec
matched any messages
.Pf ( Ql 0 )
or not
.Pf ( Ql 1 ) ;
note that any verbose output is suppressed in this mode and must instead
be enabled explicitly (e.g., by using the option
.Fl v ) .
.
.Mx
.It Fl M Ar type
Special send mode that will flag standard input with the MIME
.Ql Content-Type:
set to the given
.Ar type
and use it as the main message body.
\*(ID Using this option will bypass processing of
.Va message-inject-head ,
.Va signature
and
.Va message-inject-tail .
Also see
.Fl q , m , t .
.
.Mx
.It Fl m Ar file
Special send mode that will MIME classify the specified
.Ar file
and use it as the main message body.
\*(ID Using this option will bypass processing of
.Va message-inject-head ,
.Va signature
and
.Va message-inject-tail .
Also see
.Fl q , M , t .
.
.Mx
.It Fl N
inhibit the initial display of message headers when reading mail or
editing a mailbox
.Ic folder
by calling
.Ic unset
for the internal variable
.Va header .
.
.Mx
.It Fl n
Standard flag that inhibits reading the system wide
.Pa \*(UR
upon startup.
The option
.Fl \&:
allows more control over the startup sequence; also see
.Sx "Resource files" .
.
.Mx
.It Fl q Ar file
Special send mode that will initialize the message body with the
contents of the specified
.Ar file ,
which may be standard input
.Ql -
only in non-interactive context.
Also see
.Fl M , m , t .
.
.Mx
.It Fl R
Any mailbox
.Ic folder
opened will be in read-only mode.
.
.
.Mx
.It Fl r Ar from-addr
Whereas the source address that appears in the
.Va from
header of a message (or in the
.Va sender
header if the former contains multiple addresses) is honoured by the
builtin SMTP transport, it is not used by a file-based
.Va mta
(Mail-Transfer-Agent) for the RFC 5321 reverse-path used for relaying
and delegating a message to its destination(s), for delivery errors
etc., but it instead uses the local identity of the initiating user.
.
.Pp
When this command line option is used the given
.Ar from-addr
will be assigned to the internal variable
.Va from ,
but in addition the command line option
.Fl \&\&f Ar from-addr
will be passed to a file-based
.Va mta
whenever a message is sent.
Shall
.Ar from-addr
include a user name the address components will be separated and
the name part will be passed to a file-based
.Va mta
individually via
.Fl \&\&F Ar name .
.
.Pp
If an empty string is passed as
.Ar from-addr
then the content of the variable
.Va from
(or, if that contains multiple addresses,
.Va sender )
will be evaluated and used for this purpose whenever the file-based
.Va mta
is contacted.
By default, without
.Fl \&\&r
that is, neither
.Fl \&\&f
nor
.Fl \&\&F
command line options are used when contacting a file-based MTA, unless
this automatic deduction is enforced by
.Ic set Ns
ing the internal variable
.Va r-option-implicit .
.
.Pp
Remarks: many default installations and sites disallow overriding the
local user identity like this unless either the MTA has been configured
accordingly or the user is member of a group with special privileges.
.
.
.Mx
.It Fl S Ar var Ns Op = Ns value
.Ic set
the internal
.Ar var Ns
iable and, in case of a non-boolean variable which has a value, assign
.Ar value
to it.
Even though
.Sx "INTERNAL VARIABLES"
.Ic \&\&set
via
.Fl \&\&S
may be overwritten from within resource files,
the command line setting will be reestablished after all resource files
have been loaded.
(\*(ID In the future such a setting may instead become
.Dq frozen
until the startup is complete.)
.
.Mx
.It Fl s Ar subject
Specify the subject of the message to be sent.
Newline (NL) and carriage-return (CR) bytes are invalid and will be
normalized to space (SP) characters.
.
.Mx
.It Fl t
The message given (on standard input) is expected to contain, separated
from the message body by an empty line, a message header with
.Ql To: ,
.Ql Cc: ,
or
.Ql Bcc:
fields giving its recipients, which will be added to any recipients
specified on the command line.
If a message subject is specified via
.Ql Subject:
then it will be used in favour of one given on the command line.
.Pp
Also understood are
.Ql Reply-To:
(possibly overriding
.Va replyto ) ,
.Ql Sender:
.Pf ( Va sender ) ,
.Ql From:
.Pf ( Va from
and / or option
.Fl r ) .
.Ql Message-ID: ,
.Ql In-Reply-To: ,
.Ql References:
and
.Ql Mail-Followup-To: ,
by default created automatically dependent on message context, will
be used if specified (a special address massage will however still occur
for the latter).
Any other custom header field (also see
.Va customhdr
and
.Ic ~^ )
is passed through entirely
unchanged, and in conjunction with the options
.Fl ~
or
.Fl #
it is possible to embed
.Sx "COMMAND ESCAPES" .
Also see
.Fl M , m , q .
.
.Mx
.It Fl u Ar user
Initially read the
.Mx -sx
.Sx "primary system mailbox"
of
.Ar user ,
appropriate privileges presumed; effectively identical to
.Ql Fl \&\&f Ns \0%user .
.
.Mx
.It Fl V
Show \*(UA's
.Va version
and exit.
The command
.Ic version
will also show the list of
.Va features :
.Ql $ \*(uA -Xversion -Xx .
.
.Mx
.It Fl v
.Ic set Ns
ting the internal variable
.Va verbose
enables display of some informational context messages.
Using it twice increases the level of verbosity.
.
.Mx
.It Fl X Ar cmd
Add the given (or multiple for a multiline argument)
.Ar cmd
to the list of commands to be executed,
as a last step of program startup, before normal operation starts.
This is the only possibility to execute commands in non-interactive mode
when reading startup files is actively prohibited.
The commands will be evaluated as a unit, just as via
.Ic source .
Correlates with
.Fl #
and
.Va errexit .
.
.Mx
.It Fl ~
Enable
.Sx "COMMAND ESCAPES"
in compose mode even in non-interactive use cases.
This can be used to, e.g., automatically format the composed message
text before sending the message:
.Bd -literal -offset indent
$ ( echo 'line    one. Word.     Word2.';\e
    echo '~| /usr/bin/fmt -tuw66' ) |\e
  LC_ALL=C \*(uA -d~:/ -Sttycharset=utf-8 bob@exam.ple
.Ed
.
.Mx
.It Fl #
Enables batch mode: standard input is made line buffered, the complete
set of (interactive) commands is available, processing of
.Sx "COMMAND ESCAPES"
is enabled in compose mode, and diverse
.Sx "INTERNAL VARIABLES"
are adjusted for batch necessities, exactly as if done via
.Fl S :
.Va emptystart ,
.Pf no Va errexit ,
.Pf no Va header ,
.Pf no Va posix ,
.Va quiet ,
.Va sendwait ,
.Va typescript-mode
as well as
.Ev MAIL ,
.Ev MBOX
and
.Va inbox
(the latter three to
.Pa /dev/null ) .
The following prepares an email message in a batched dry run:
.Bd -literal -offset indent
$ LC_ALL=C printf 'm bob\en~s ubject\enText\en~.\enx\en' |\e
  LC_ALL=C \*(uA -d#:/ -X'alias bob bob@exam.ple'
.Ed
.
.Mx
.It Fl \&.
This flag forces termination of option processing in order to prevent
.Dq option injection
(attacks).
It also forcefully puts \*(UA into send mode, see
.Sx "On sending mail, and non-interactive mode" .
.El
.
.Pp
All given
.Ar to-addr
arguments and all receivers established via
.Fl b
and
.Fl c
are subject to the checks established by
.Va expandaddr ,
one of the
.Sx "INTERNAL VARIABLES" .
If the setting of
.Va expandargv
allows their recognition all
.Ar mta-option
arguments given at the end of the command line after a
.Ql --
separator will be passed through to a file-based
.Va mta
(Mail-Transfer-Agent) and persist for the entire session.
.Va expandargv
constraints do not apply to the content of
.Va mta-arguments .
.\" }}}
.
.\" .Ss "A starter" {{{
.Ss "A starter"
.
\*(UA is a direct descendant of
.Bx
Mail, itself a successor of the Research
.Ux
mail which
.Dq was there from the start
according to
.Sx HISTORY .
It thus represents the user side of the
.Ux
mail system, whereas the system side (Mail-Transfer-Agent, MTA) was
traditionally taken by
.Xr sendmail 8 ,
and most MTAs provide a binary of this name for compatibility purposes.
If the \*(OPal SMTP
.Va mta
is included in the
.Va features
of \*(UA then the system side is not a mandatory precondition for mail
delivery.
.
.Pp
Because \*(UA strives for compliance with POSIX
.Xr mailx 1
it is likely that some configuration settings have to be adjusted before
using it is a smooth experience.
(Rather complete configuration examples can be found in the section
.Sx EXAMPLES . )
The default global
.Pa \*(UR
resource file bends those standard imposed settings of the
.Sx "INTERNAL VARIABLES"
a bit towards more user friendliness and safety already.
.
.Pp
For example, it
.Ic set Ns s
.Va hold
and
.Va keepsave
in order to suppress the automatic moving of messages to the
.Mx -sx
.Sx "secondary mailbox"
.Ev MBOX
that would otherwise occur (see
.Sx "Message states" ) ,
and
.Va keep
to not remove empty system MBOX mailbox files in order not to mangle
file permissions when files eventually get recreated (all empty (MBOX)
mailbox files will be removed unless this variable is set whenever
.Ev POSIXLY_CORRECT
mode has been enabled).
.
.Pp
It also enables
.Va sendwait
in order to synchronize \*(UA with the exit status report of the used
.Va mta
when sending mails.
It
.Ic set Ns
s
.Va emptystart
to enter interactive startup even if the initial mailbox is empty,
.Va editheaders
to allow editing of headers as well as
.Va fullnames
to not strip down addresses in compose mode, and
.Va quote
to include the message that is being responded to when
.Ic reply Ns
ing.
.
.Pp
It should be remarked that the file mode creation mask can be
explicitly managed via the variable
.Va umask .
\*(UA will not follow symbolic links when opening files for writing,
sufficient system support provided.
.\" }}}
.
.\" .Ss "On sending mail, and non-interactive mode" {{{
.Ss "On sending mail, and non-interactive mode"
.
To send a message to one or more people, using a local or a built-in
.Va mta
(Mail-Transfer-Agent) transport to actually deliver the generated mail
message, \*(UA can be invoked with arguments which are the names of
people to whom the mail will be sent, and the command line options
.Fl b
and
.Fl c
can be used to add (blind) carbon copy receivers:
.
.Bd -literal -offset indent
# Via sendmail(1)
$ \*(uA -s ubject -a ttach.txt bill@exam.ple

# But... try it in an isolated dry-run mode (-d) first
$ LC_ALL=C \*(uA -d -:/ -Ssendwait -Sttycharset=utf8 \e
   -b bcc@exam.ple -c cc@exam.ple \e
   -. '(Lovely) Bob <bob@exam.ple>' eric@exam.ple

# With SMTP
$ LC_ALL=C \*(uA -d -:/ -Sv15-compat -Ssendwait -Sttycharset=utf8 \e
    -S mta=smtps://mylogin@exam.ple:465 -Ssmtp-auth=none \e
    -S from=scriptreply@exam.ple \e
    -a /etc/mail.rc \e
    -. eric@exam.ple
.Ed
.
.Pp
If standard input is a terminal rather than the message to be sent,
the user is expected to type in the message contents.
In this compose mode \*(UA treats lines beginning with the character
.Ql ~
special \(en these are so-called
.Sx "COMMAND ESCAPES" ,
which can be used to read in files, process shell commands, add and edit
attachments and more; e.g., the command escape
.Ic ~e
will start the text editor to revise the message in its current state,
.Ic ~h
allows editing of the most important message headers, with
.Ic ~^
custom headers can be created (more specifically than with
.Va customhdr ) .
.Ic ~?
gives an overview of most other available command escapes.
Typing
.Ql control-D
.Pf ( Ql ^D )
at the beginning of an empty line leaves compose mode and causes the
message to be sent, whereas typing
.Ql control-C
.Pf ( Ql ^C )
twice will abort the current letter (saving its contents in the file
denoted by
.Ev DEAD
unless
.Pf no Va save
is set).
.
.Pp
A number of
.Sx ENVIRONMENT
and
.Sx "INTERNAL VARIABLES"
can be used to alter default behavior.
E.g., messages are sent asynchronously, without supervision, unless the
internal variable
.Va sendwait
is set, therefore send errors will not be recognizable until then.
.Ic set Ns
ting (also via
.Fl S )
.Va editalong
will automatically startup a text editor when compose mode is entered,
.Va editheaders
allows editing of headers additionally to plain body content, whereas
.Va askcc
and
.Va askbcc
will cause the user to be prompted actively for (blind) carbon-copy
recipients, respectively, if the given list is empty.
.
.Pp
Especially when using public mail provider accounts with the SMTP
.Va mta
it is often necessary to set
.Va from
and/or
.Va hostname
(even finer control via
.Va smtp-hostname ) ,
which (even if empty) also causes creation of
.Ql Message-ID:
and
.Ql Content-ID:
header fields unless
.Va stealthmua
is set.
Saving a copy of sent messages in a
.Va record
mailbox may be desirable \(en as for most mailbox
.Ic file
targets the value will undergo
.Sx "Filename transformations" .
Defining user email
.Ic account Ns s
for the purpose of arranging a complete environment of settings that can
be switched to with a single command or command line option may be
useful.
.Pf ( Sx EXAMPLES
has example configurations for some of the well-known public mail
providers, and also gives a compact overview on how to setup a secure
SSL/TLS environment.)
Some introductional
.Fl d
or
.Va debug
sandbox dry-run tests will prove correctness.
.
.Pp
The section
.Sx "On URL syntax and credential lookup"
will spread light on the different ways of how to specify user email
account credentials, the
.Ql USER@HOST
variable chains, and accessing protocol-specific resources,
the section
.Sx "Character sets"
goes into the details of character encodings, and how to use them for
interpreting the input data given in
.Va ttycharset
and representing messages and MIME part contents in
.Va sendcharsets ,
and reading the section
.Sx "The mime.types files"
should help to understand how the MIME-type of outgoing attachments are
classified, and what can be done for fine-tuning.
Over the wire a configurable
.Va mime-encoding
.Pf ( Ql Content-Transfer-Encoding: )
may be applied to the message data.
.
.Pp
Message recipients (as specified on the command line or defined in
.Ql To: ,
.Ql Cc:
or
.Ql Bcc: )
may not only be email addressees but can also be names of mailboxes and
even complete shell command pipe specifications.
If the variable
.Va expandaddr
is not set then only network addresses (see
.Xr mailaddr 7
for a description of mail addresses) and plain user names (including MTA
aliases) may be used, other types will be filtered out, giving a warning
message.
The command
.Ic addrcodec
can be used to generate standard compliant network addresses.
.
.\" When changing any of the following adjust any RECIPIENTADDRSPEC;
.\" grep the latter for the complete picture
.Pp
If the variable
.Va expandaddr
is set then extended recipient addresses will optionally be accepted:
Any name which starts with a vertical bar
.Ql |
character specifies a command pipe \(en the command string following the
.Ql |
is executed and the message is sent to its standard input;
Likewise, any name that starts with the character solidus
.Ql /
or the character sequence dot solidus
.Ql ./
is treated as a file, regardless of the remaining content;
likewise a name that solely consists of a hyphen-minus
.Ql - .
Any other name which contains a commercial at
.Ql @
character is treated as a network address;
Any other name which starts with a plus sign
.Ql +
character specifies a mailbox name;
Any other name which contains a solidus
.Ql /
character but no exclamation mark
.Ql \&!
or percent sign
.Ql %
character before also specifies a mailbox name;
What remains is treated as a network address.
.
.Bd -literal -offset indent
$ echo bla | \*(uA -Sexpandaddr -s test ./mbox.mbox
$ echo bla | \*(uA -Sexpandaddr -s test '|cat >> ./mbox.mbox'
$ echo safe | LC_ALL=C \e
    \*(uA -:/ -Sv15-compat -Ssendwait -Sttycharset=utf8 \e
      -Sexpandaddr=fail,-all,+addr,failinvaddr -s test \e
      -. bob@exam.ple
.Ed
.
.Pp
It is possible to create personal distribution lists via the
.Ic alias
command, so that, for instance, the user can send mail to
.Ql cohorts
and have it go to a group of people.
These aliases have nothing in common with the system wide aliases that
may be used by the MTA, which are subject to the
.Ql name
constraint of
.Va expandaddr
and are often tracked in a file
.Pa /etc/aliases
(and documented in
.Xr aliases 5
and
.Xr sendmail 1 ) .
Personal aliases will be expanded by \*(UA before the message is sent,
and are thus a convenient alternative to specifying each addressee by
itself; they correlate with the active set of
.Ic alternates
and are subject to
.Va metoo
filtering.
.
.Pp
.Dl alias cohorts bill jkf mark kridle@ucbcory ~/mail/cohorts.mbox
.
.Pp
.Va on-compose-enter , on-compose-leave
and
.Va on-compose-cleanup
hook variables may be set to
.Ic define Ns
d macros to automatically adjust some settings dependent
on receiver, sender or subject contexts, and via the
.Va on-compose-splice
as well as
.Va on-compose-splice-shell
variables, the former also to be set to a
.Ic define Ns
d macro, increasingly powerful mechanisms to perform automated message
adjustments are available.
(\*(ID These hooks work for commands which newly create messages, namely
.Ic forward , mail , reply
and variants;
.Ic resend
and
.Ic Resend
for now provide only the hooks
.Va on-resend-enter
and
.Va on-resend-cleanup . )
.
.Pp
To avoid environmental noise scripts should
.Dq detach
\*(UA from any configuration files and create a script-local
environment, ideally with the command line options
.Fl \&:
to disable any configuration file in conjunction with repetitions of
.Fl S
to specify variables:
.
.Bd -literal -offset indent
$ env LC_ALL=C \*(uA -:/ \e
    -Sv15-compat -Ssendwait -Sttycharset=utf-8 \e
    -Sexpandaddr=fail,-all,failinvaddr \e
    -S mta=smtps://mylogin@exam.ple:465 -Ssmtp-auth=login \e
    -S from=scriptreply@exam.ple \e
    -s 'Subject to go' -a attachment_file \e
    -. 'Recipient 1 <rec1@exam.ple>' rec2@exam.ple \e
    < content_file
.Ed
.
.Pp
As shown, scripts can
.Dq fake
a locale environment, the above specifies the all-compatible 7-bit clean
.Ev LC_ALL
.Dq C ,
but will nonetheless take and send UTF-8 in the message text by using
.Va ttycharset .
In interactive mode, which is introduced in the next section, messages
can be sent by calling the
.Ic mail
command with a list of recipient addresses:
.
.Bd -literal -offset indent
$ \*(uA -d -Squiet -Semptystart
"/var/spool/mail/user": 0 messages
? mail "Recipient 1 <rec1@exam.ple>", rec2@exam.ple
...
? # Will do the right thing (tm)
? m rec1@exam.ple rec2@exam.ple
.Ed
.\" }}}
.
.\" .Ss "On reading mail, and interactive mode" {{{
.Ss "On reading mail, and interactive mode"
.
When invoked without addressees \*(UA enters interactive mode in which
mails may be read.
When used like that the user's system
.Va inbox
(for more on mailbox types please see the command
.Ic file )
is read in and a one line header of each message therein is displayed if
the variable
.Va header
is set.
The visual style of this summary of
.Ic headers
can be adjusted through the variable
.Va headline
and the possible sorting criterion via
.Va autosort .
Scrolling through
.Va screen Ns
fuls of
.Ic headers
can be performed with the command
.Ic z .
If the initially opened mailbox is empty \*(UA will instead exit
immediately (after displaying a message) unless the variable
.Va emptystart
is set.
.
.Pp
At the
.Va prompt
the command
.Ic list
will give a listing of all available commands and
.Ic help
will give a summary of some common ones.
If the \*(OPal documentation strings are available one can type
.Ql help X
.Pf "(or " Ql ?X )
and see the actual expansion of
.Ql X
and what its purpose is, i.e., commands can be abbreviated
(note that POSIX defines some abbreviations, so that the alphabetical
order of commands does not necessarily relate to the abbreviations; it is
however possible to define overwrites with
.Ic commandalias ) .
These commands can also produce a more
.Va verbose
output.
.
.Pp
Messages are given numbers (starting at 1) which uniquely identify
messages; the current message \(en the
.Dq dot
\(en will either be the first new message, or the first unread message,
or the first message of the mailbox; the internal variable
.Va showlast
will instead cause usage of the last message for this purpose.
The command
.Ic headers
will display a
.Va screen Ns
ful of header summaries containing the
.Dq dot ,
whereas
.Ic from
will display only the summaries of the given messages, defaulting to the
.Dq dot .
.
.Pp
Message content can be displayed with the command
.Ic type
.Pf ( Ql t ,
alias
.Ic print ) .
Here the variable
.Va crt
controls whether and when \*(UA will use the configured
.Ev PAGER
for display instead of directly writing to the user terminal
.Va screen ,
the sole difference to the command
.Ic more ,
which will always use the
.Ev PAGER .
The command
.Ic top
will instead only show the first
.Va toplines
of a message (maybe even compressed if
.Va topsqueeze
is set).
Message display experience may improve by setting and adjusting
.Va mime-counter-evidence ,
and also see
.Sx "HTML mail and MIME attachments" .
.
.Pp
By default the current message
.Pf ( Dq dot )
is displayed, but like with many other commands it is possible to give
a fancy message specification (see
.Sx "Specifying messages" ) ,
e.g.,
.Ql t:u
will display all unread messages,
.Ql t.
will display the
.Dq dot ,
.Ql t 1 5
will type the messages 1 and 5,
.Ql t 1-5
will type the messages 1 through 5, and
.Ql t-
and
.Ql t+
will display the last and the next message, respectively.
The command
.Ic search
(a more substantial alias for
.Ic from )
will display a header summary of the given message specification list
instead of their content, e.g., the following will search for subjects:
.
.Pp
.Dl ? from "'@Some subject to search for'"
.
.Pp
In the default setup all header fields of a message will be
.Ic type Ns
d, but fields can be white- or blacklisted for a variety of
applications by using the command
.Ic headerpick ,
e.g., to restrict their display to a very restricted set for
.Ic type :
.Ql Ic \:headerpick Cd \:type retain Ar \:from to cc subject .
In order to display all header fields of a message regardless of
currently active ignore or retain lists, use the commands
.Ic Type
and
.Ic Top ;
.Ic Show
will show the raw message content.
Note that historically the global
.Pa \*(UR
not only adjusts the list of displayed headers, but also sets
.Va crt .
.
.Pp
Dependent upon the configuration a line editor (see the section
.Sx "On terminal control and line editor" )
aims at making the user experience with the many
.Sx COMMANDS
a bit nicer.
When reading the system
.Va inbox
or when
.Fl f
(or
.Ic file )
specified a mailbox explicitly prefixed with the special
.Ql %:
modifier (propagating the mailbox to a
.Mx -sx
.Sx "primary system mailbox" ) ,
then messages which have been read will be automatically moved to a
.Mx -sx
.Sx "secondary mailbox" ,
the users
.Ev MBOX
file, when the mailbox is left, either by changing the
active mailbox or by quitting \*(UA (also see
.Sx "Message states" )
\(en this automatic moving from a system or primary to the secondary
mailbox is not performed when the variable
.Va hold
is set.
Messages can also be explicitly
.Ic move Ns
d to other mailboxes, whereas
.Ic copy
keeps the original message.
.Ic write
can be used to write out data content of specific parts of messages.
.
.Pp
After examining a message the user can
.Ic reply Ql r
to the sender and all recipients (which will also be placed in
.Ql To:
unless
.Va recipients-in-cc
is set) or
.Ic Reply Ql R
exclusively to the sender(s).
.Ic forward Ns
ing a message will allow editing the new message: the original message
will be contained in the message body, adjusted according to
.Ic headerpick .
When replying to or forwarding a message recipient addresses will be
stripped from comments and names unless the internal variable
.Va fullnames
is set.
It is possible to
.Ic resend
or
.Ic Resend
messages: the former will add a series of
.Ql Resent-
headers, whereas the latter will not; different to newly created
messages editing is not possible and no copy will be saved even with
.Va record
unless the additional variable
.Va record-resent
is set.
Of course messages can be
.Ic delete Ql d ,
and they can spring into existence again via
.Ic undelete
or when the \*(UA session is ended via the
.Ic exit Ql x
command.
.
.Pp
To end a mail processing session one may either issue
.Ic quit Ql q
to cause a full program exit, which possibly includes
automatic moving of read messages to the
.Mx -sx
.Sx "secondary mailbox"
.Ev MBOX
as well as updating the \*(OPal line editor
.Va history-file ,
or use the command
.Ic exit Ql x
instead in order to prevent any of these actions.
.\" }}}
.
.\" .Ss "HTML mail and MIME attachments" {{{
.Ss "HTML mail and MIME attachments"
.
Messages which are HTML-only become more and more common and of course
many messages come bundled with a bouquet of MIME (Multipurpose Internet
Mail Extensions) parts for, e.g., attachments.
To get a notion of MIME types, \*(UA will first read
.Sx "The mime.types files"
(as configured and allowed by
.Va mimetypes-load-control ) ,
and then add onto that types registered directly with
.Ic mimetype .
It (normally) has a default set of types built-in, too.
To improve interaction with faulty MIME part declarations which are
often seen in real-life messages, setting
.Va mime-counter-evidence
will allow \*(UA to verify the given assertion and possibly provide
an alternative MIME type.
.
.Pp
Whereas \*(UA \*(OPally supports a simple HTML-to-text converter for
HTML messages, it cannot handle MIME types other than plain text itself.
Instead programs need to become registered to deal with specific MIME
types or file extensions.
These programs may either prepare plain text versions of their input in
order to enable \*(UA to integrate their output neatlessly in its own
message visualization (a mode which is called
.Cd copiousoutput ) ,
or display the content themselves, for example in an external graphical
window: such handlers will only be considered by and for the command
.Ic mimeview .
.
.Pp
To install a handler program for a specific MIME type an according
.Va pipe-TYPE/SUBTYPE
variable needs to be set; to instead define a handler for a specific
file extension the respective
.Va pipe-EXTENSION
variable can be used \(en these handlers take precedence.
\*(OPally \*(UA supports mail user agent configuration as defined in
RFC 1524; this mechanism (see
.Sx "The Mailcap files" )
will be queried for display or quote handlers if none of the former two
.\" TODO v15-compat "will be" -> "is"
did; it will be the sole source for handlers of other purpose.
A last source for handlers is the MIME type definition itself, when
a (\*(UA specific) type-marker was registered with the command
.Ic mimetype
(which many built-in MIME types do).
.
.Pp
E.g., to display a HTML message inline (that is, converted to a more
fancy plain text representation than the built-in converter is capable to
produce) with either of the text-mode browsers
.Xr lynx 1
or
.Xr elinks 1 ,
teach \*(UA about MathML documents and make it display them as plain
text, and to open PDF attachments in an external PDF viewer,
asynchronously and with some other magic attached:
.
.Bd -literal -offset indent
? if [ "$features" !% +filter-html-tagsoup ]
?  #set pipe-text/html='@* elinks -force-html -dump 1'
?  set pipe-text/html='@* lynx -stdin -dump -force_html'
?  # Display HTML as plain text instead
?  #set pipe-text/html=@
? endif
? mimetype @ application/mathml+xml mathml
? wysh set pipe-application/pdf='@&=@ \e
    trap "rm -f \e"${MAILX_FILENAME_TEMPORARY}\e"" EXIT;\e
    trap "trap \e"\e" INT QUIT TERM; exit 1" INT QUIT TERM;\e
    mupdf "${MAILX_FILENAME_TEMPORARY}"'
.Ed
.\" }}}
.
.\" .Ss "Mailing lists" {{{
.Ss "Mailing lists"
.
\*(UA offers some support to ease handling of mailing lists.
The command
.Ic mlist
promotes all given arguments to known mailing lists, and
.Ic mlsubscribe
sets their subscription attribute, creating them first as necessary.
(On the other hand
.Ic unmlsubscribe
does not
.Ic unmlist
automatically, but only resets the subscription attribute.)
Using the commands without arguments will show (a subset of) all
currently defined mailing lists.
The
.Va headline
format
.Ql \&%T
can be used to mark out messages with configured list addresses
in the header display.
.
.Pp
\*(OPally mailing lists may also be specified as (extended) regular
expressions, which allows matching of many addresses with a single
expression.
However, all fully qualified list addresses are matched via a fast
dictionary, whereas expressions are placed in (a) list(s) which is
(are) matched sequentially.
.
.Bd -literal -offset indent
? set followup-to followup-to-honour=ask-yes \e
    reply-to-honour=ask-yes
? wysh mlist a1@b1.c1 a2@b2.c2 '.*@lists\e.c3$'
? mlsubscribe a4@b4.c4 exact@lists.c3
.Ed
.
.Pp
The variable
.Va followup-to-honour
will ensure that a
.Ql Mail-\:Followup-\:To:
header is honoured when the message is being replied to (via
.Ic reply
and
.Ic Lreply )
and
.Va followup-to
controls whether this header is created when sending mails; it will be
created automatically for a couple of reasons, too, like when the
special
.Dq mailing list specific
respond command
.Ic Lreply
is used, when
.Ic reply
is used to respond to a message with its
.Ql Mail-Followup-To:
being honoured etc.
.
.Pp
A difference in between the handling of known and subscribed lists is
that the address of the sender is usually not part of a generated
.Ql Mail-Followup-To:
when addressing the latter, whereas it is for the former kind of lists.
Usually because there are exceptions: say, if multiple lists are
addressed and not all of them are subscribed lists.
.Pp
For convenience \*(UA will, temporarily, automatically add a list
address that is presented in the
.Ql List-Post:
header of a message that is being responded to to the list of known
mailing lists.
Shall that header have existed \*(UA will instead, dependent on the
variable
.Va reply-to-honour ,
use an also set
.Ql Reply-To:
for this purpose in order to accept a list administrators' wish that
is supposed to have been manifested like that (but only if it provides
a single address which resides on the same domain as what is stated in
.Ql List-Post: ) .
.\" }}}
.
.\" .Ss "Signed and encrypted messages with S/MIME" {{{
.Ss "Signed and encrypted messages with S/MIME"
.
\*(OP S/MIME provides two central mechanisms:
message signing and message encryption.
A signed message contains some data in addition to the regular text.
The data can be used to verify that the message was sent using a valid
certificate, that the sender's address in the message header matches
that in the certificate, and that the message text has not been altered.
Signing a message does not change its regular text;
it can be read regardless of whether the recipient's software is able to
handle S/MIME.
It is thus usually possible to sign all outgoing messages if so desired.
.
.Pp
Encryption, in contrast, makes the message text invisible for all people
except those who have access to the secret decryption key.
To encrypt a message, the specific recipient's public encryption key
must be known.
It is therefore not possible to send encrypted mail to people unless their
key has been retrieved from either previous communication or public key
directories.
A message should always be signed before it is encrypted.
Otherwise, it is still possible that the encrypted message text is
altered.
.
.Pp
A central concept to S/MIME is that of the certification authority (CA).
A CA is a trusted institution that issues certificates.
For each of these certificates it can be verified that it really
originates from the CA, provided that the CA's own certificate is
previously known.
A set of CA certificates is usually delivered with OpenSSL and installed
on your system.
If you trust the source of your OpenSSL software installation,
this offers reasonable security for S/MIME on the Internet.
Otherwise set
.Va smime-ca-no-defaults
to avoid using the default certificates and point
.Va smime-ca-file
and/or
.Va smime-ca-dir
to a trusted pool of certificates.
In general, a certificate cannot be more secure than the method its CA
certificate has been retrieved with.
.
.Pp
This trusted pool of certificates is used by the command
.Ic verify
to ensure that the given S/MIME messages can be trusted.
If so, verified sender certificates that were embedded in signed
messages can be saved locally with the command
.Ic certsave ,
and used by \*(UA to encrypt further communication with these senders:
.
.Bd -literal -offset indent
? certsave FILENAME
? set smime-encrypt-USER@HOST=FILENAME \e
    smime-cipher-USER@HOST=AES256
.Ed
.
.Pp
To sign outgoing messages in order to allow receivers to verify the
origin of these messages a personal S/MIME certificate is required.
\*(UA supports password-protected personal certificates (and keys),
for more on this, and its automatization, please see the section
.Sx "On URL syntax and credential lookup" .
The section
.Sx "S/MIME step by step"
shows examplarily how such a private certificate can be obtained.
In general, if such a private key plus certificate
.Dq pair
is available, all that needs to be done is to set some variables:
.
.Bd -literal -offset indent
? set smime-sign-cert=ME@HERE.com.paired \e
    smime-sign-message-digest=SHA256 \e
    smime-sign
.Ed
.
.Pp
Variables of interest for S/MIME in general are
.Va smime-ca-dir ,
.Va smime-ca-file ,
.Va smime-ca-flags ,
.Va smime-ca-no-defaults ,
.Va smime-crl-dir ,
.Va smime-crl-file .
For S/MIME signing of interest are
.Va smime-sign ,
.Va smime-sign-cert ,
.Va smime-sign-include-certs
and
.Va smime-sign-message-digest .
Additional variables of interest for S/MIME en- and decryption:
.Va smime-cipher
and
.Va smime-encrypt-USER@HOST .
.
.Pp
\*(ID Note that neither S/MIME signing nor encryption applies to
message subjects or other header fields yet.
Thus they may not contain sensitive information for encrypted messages,
and cannot be trusted even if the message content has been verified.
When sending signed messages,
it is recommended to repeat any important header information in the
message text.
.\" }}}
.
.\" .Ss "On URL syntax and credential lookup" {{{
.Ss "On URL syntax and credential lookup"
.
\*(IN For accessing protocol-specific resources usage of Uniform
Resource Locators (URL, RFC 1738) has become omnipresent.
\*(UA expects and understands URLs in the following form;
parts in brackets
.Ql []
denote optional parts, optional either because there also exist other
ways to define the information in question or because support of the
part is protocol-specific (e.g.,
.Ql /path
is used by the local maildir and the IMAP protocol, but not by POP3);
If any of
.Ql USER
and
.Ql PASSWORD
are specified they must be given in URL percent encoded form (RFC 3986;
the command
.Ic urlcodec
may be helpful):
.
.Pp
.Dl PROTOCOL://[USER[:PASSWORD]@]server[:port][/path]
.
.Pp
Note that these \*(UA URLs most often do not conform to any real
standard, but instead represent a normalized variant of RFC 1738 \(en
they are not used in data exchange but only meant as a compact,
easy-to-use way of defining and representing information in
a well-known notation.
.
.Pp
Many internal variables of \*(UA exist in multiple versions, called
variable chains for the rest of this document: the plain
.Ql variable
as well as
.Ql variable-HOST
and
.Ql variable-USER@HOST .
Here
.Ql HOST
indeed means
.Ql server:port
if a
.Ql port
had been specified in the respective URL, otherwise it refers to the plain
.Ql server .
Also,
.Ql USER
is not truly the
.Ql USER
that had been found when doing the user chain lookup as is described
below, i.e., this
.Ql USER
will never be in URL percent encoded form, whether it came from an URL
or not; i.e., variable chain name extensions of
.Sx "INTERNAL VARIABLES"
must not be URL percent encoded.
.
.Pp
For example, whether an hypothetical URL
.Ql smtp://hey%3Ayou@our.house
had been given that includes a user, or whether the URL was
.Ql smtp://our.house
and the user had been found differently, to lookup the variable chain
.Va smtp-use-starttls
\*(UA first looks for whether
.Ql smtp-\:use-\:starttls-\:hey:you@our.house
is defined, then whether
.Ql smtp-\:use-\:starttls-\:our.house
exists before finally ending up looking at the plain variable itself.
.
.Pp
\*(UA obeys the following logic scheme when dealing with the
necessary credential information of an account:
.
.Bl -bullet
.It
If no
.Ql USER
has been given in the URL the variables
.Va user-HOST
and
.Va user
are looked up; if no such variable(s) can be found then \*(UA will,
when enforced by the \*(OPal variables
.Va netrc-lookup-HOST
or
.Va netrc-lookup ,
search the users
.Pa .netrc
file for a
.Ql HOST
specific entry which provides a
.Ql login
name: this lookup will only succeed if unambiguous (one possible matching
entry for
.Ql HOST ) .
It is possible to load encrypted
.Pa .netrc
files via
.Va netrc-pipe .
.Pp
If there is still no
.Ql USER
then \*(UA will fall back to the user who is supposed to run \*(UA,
the identity of which has been fixated during \*(UA startup and is
known to be a valid user on the current host.
.
.It
Authentication: unless otherwise noted this will lookup the
.Va PROTOCOL-auth-USER@HOST , PROTOCOL-auth-HOST , PROTOCOL-auth
variable chain, falling back to a protocol-specific default should this
have no success.
.
.It
If no
.Ql PASSWORD
has been given in the URL, then if the
.Ql USER
has been found through the \*(OPal
.Va netrc-lookup
that may have already provided the password, too.
Otherwise the variable chain
.Va password-USER@HOST , password-HOST , password
is looked up and used if existent.
.Pp
Afterwards the complete \*(OPal variable chain
.Va netrc-lookup-USER@HOST , netrc-lookup-HOST , netrc-lookup
is looked up.
If set, the
.Ic netrc
cache is searched for a password only (multiple user accounts for
a single machine may exist as well as a fallback entry without user
but with a password).
.Pp
If at that point there is still no password available, but the
(protocols') chosen authentication type requires a password, then in
interactive mode the user will be prompted on the terminal.
.El
.
.Pp
.Sy Note:
S/MIME verification works relative to the values found in the
.Ql From:
(or
.Ql Sender: )
header field(s), which means that the values of
.Va smime-sign , smime-sign-cert , smime-sign-include-certs
and
.Va smime-sign-message-digest
will not be looked up using the
.Ql USER
and
.Ql HOST
chains from above but instead use the corresponding values from the
message that is being worked on.
In unusual cases multiple and different
.Ql USER
and
.Ql HOST
combinations may therefore be involved \(en on the other hand those
unusual cases become possible.
The usual case is as short as:
.
.Pp
.Dl set mta=smtp://USER:PASS@HOST smtp-use-starttls \e
.Dl \ \ \ \ smime-sign smime-sign-cert=+smime.pair
.
.Pp
The section
.Sx EXAMPLES
contains complete example configurations.
.\" }}}
.
.\" .Ss "Character sets" {{{
.Ss "Character sets"
.
\*(OP \*(UA detects the character set of the terminal by using
mechanisms that are controlled by the
.Ev LC_CTYPE
environment variable
(in fact
.Ev LC_ALL ,
.Ev \&\&LC_CTYPE ,
.Ev LANG ,
in that order, see there).
The internal variable
.Va ttycharset
will be set to the detected terminal character set accordingly,
and will thus show up in the output of commands like, e.g.,
.Ic set
and
.Ic varshow .
.
.Pp
However, the user may give a value for
.Va ttycharset
during startup, so that it is possible to send mail in a completely
.Dq faked
locale environment, an option which can be used to generate and send,
e.g., 8-bit UTF-8 input data in a pure 7-bit US-ASCII
.Ql LC_ALL=C
environment (an example of this can be found in the section
.Sx "On sending mail, and non-interactive mode" ) .
Changing the value does not mean much beside that, because several
aspects of the real character set are implied by the locale environment
of the system, which stays unaffected by
.Va ttycharset .
.
.Pp
If the \*(OPal character set conversion capabilities are not available
.Pf ( Va features
does not include the term
.Ql +iconv ) ,
then
.Va ttycharset
will be the only supported character set,
it is simply assumed that it can be used to exchange 8-bit messages
(over the wire an intermediate, configurable
.Va mime-encoding
may be applied),
and the rest of this section does not apply;
it may however still be necessary to explicitly set it if automatic
detection fails, since in that case it defaults to
.\" (Keep in SYNC: ./nail.1:"Character sets", ./config.h:CHARSET_*!)
LATIN1 a.k.a. ISO-8859-1.
.
.Pp
\*(OP When reading messages, their text is converted into
.Va ttycharset
as necessary in order to display them on the users terminal.
Unprintable characters and invalid byte sequences are detected
and replaced by proper substitution characters.
Character set mappings for source character sets can be established with
the command
.Ic charsetalias ,
which may be handy to work around faulty character set catalogues (e.g.,
to add a missing LATIN1 to ISO-8859-1 mapping), or to enforce treatment
of one character set as another one (e.g., to interpret LATIN1 as CP1252).
Also see
.Va charset-unknown-8bit
to deal with another hairy aspect of message interpretation.
.
.Pp
When sending messages all their parts and attachments are classified.
Whereas no character set conversion is performed on those parts which
appear to be binary data,
the character set being used must be declared within the MIME header of
an outgoing text part if it contains characters that do not conform to
the set of characters that are allowed by the email standards.
Permissible values for character sets used in outgoing messages can be
declared using the
.Va sendcharsets
variable, and
.Va charset-8bit ,
which defines a catch-all last-resort fallback character set that is
implicitly appended to the list of character sets in
.Va sendcharsets .
.
.Pp
When replying to a message and the variable
.Va reply-in-same-charset
is set, then the character set of the message being replied to
is tried first (still being a subject of
.Ic charsetalias ) .
And it is also possible to make \*(UA work even more closely related to
the current locale setting automatically by using the variable
.Va sendcharsets-else-ttycharset ,
please see there for more information.
.
.Pp
All the specified character sets are tried in order unless the
conversion of the part or attachment succeeds.
If none of the tried (8-bit) character sets is capable to represent the
content of the part or attachment,
then the message will not be sent and its text will optionally be
.Va save Ns d
in
.Ev DEAD .
In general, if a message saying
.Dq cannot convert from a to b
appears, either some characters are not appropriate for the currently
selected (terminal) character set,
or the needed conversion is not supported by the system.
In the first case, it is necessary to set an appropriate
.Ev LC_CTYPE
locale and/or the variable
.Va ttycharset .
.
.Pp
The best results are usually achieved when \*(UA is run in a UTF-8
locale on an UTF-8 capable terminal, in which case the full Unicode
spectrum of characters is available.
In this setup characters from various countries can be displayed,
while it is still possible to use more simple character sets for sending
to retain maximum compatibility with older mail clients.
.
.Pp
On the other hand the POSIX standard defines a locale-independent 7-bit
.Dq portable character set
that should be used when overall portability is an issue, the even more
restricted subset named
.Dq portable filename character set
consists of A-Z, a-z, 0-9, period
.Ql \&. ,
underscore
.Ql _
and hyphen-minus
.Ql - .
.\" }}}
.
.\" .Ss "Message states" {{{
.Ss "Message states"
.
\*(UA differentiates in between several different message states;
the current state will be reflected in header summary displays if
.Va headline
is configured to do so (via the internal variable
.Va attrlist ) ,
and messages can also be selected and be acted upon depending on their
state (see
.Sx "Specifying messages" ) .
When operating on the system
.Va inbox ,
or in any other
.Mx -sx
.Sx "primary system mailbox" ,
special actions, like the automatic moving of messages to the
.Mx -sx
.Sx "secondary mailbox"
.Ev MBOX ,
may be applied when the mailbox is left (also implicitly via
a successful exit of \*(UA, but not if the special command
.Ic exit
is used) \(en however, because this may be irritating to users which
are used to
.Dq more modern
mail-user-agents, the default global
.Pa \*(UR
sets the internal
.Va hold
and
.Va keepsave
variables in order to suppress this behaviour.
.
.Bl -hang -width ".It Ql new"
.It Ql new
Message has neither been viewed nor moved to any other state.
Such messages are retained even in the
.Mx -sx
.Sx "primary system mailbox" .
.
.It Ql unread
Message has neither been viewed nor moved to any other state, but the
message was present already when the mailbox has been opened last:
Such messages are retained even in the
.Mx -sx
.Sx "primary system mailbox" .
.
.It Ql read
The message has been processed by one of the following commands:
.Ic ~f ,
.Ic ~m ,
.Ic ~F ,
.Ic ~M ,
.Ic copy ,
.Ic mbox ,
.Ic next ,
.Ic pipe  ,
.Ic Print ,
.Ic print ,
.Ic top ,
.Ic Type ,
.Ic type ,
.Ic undelete .
The commands
.Ic dp
and
.Ic dt
will always try to automatically
.Dq step
and
.Ic type
the
.Dq next
logical message, and may thus mark multiple messages as read, the
.Ic delete
command will do so if  the internal variable
.Va autoprint
is set.
Except when the
.Ic exit
command is used, messages that are in a
.Mx -sx
.Sx "primary system mailbox"
and are in
.Ql read
state when the mailbox is left will be saved in the
.Mx -sx
.Sx "secondary mailbox"
.Ev MBOX
unless the internal variable
.Va hold
it set.
.
.It Ql deleted
The message has been processed by one of the following commands:
.Ic delete ,
.Ic dp ,
.Ic dt .
Only
.Ic undelete
can be used to access such messages.
.
.It Ql preserved
The message has been processed by a
.Ic preserve
command and it will be retained in its current location.
.
.It Ql saved
The message has been processed by one of the following commands:
.Ic save
or
.Ic write .
Unless when the
.Ic exit
command is used, messages that are in a
.Mx -sx
.Sx "primary system mailbox"
and are in
.Ql saved
state when the mailbox is left will be deleted; they will be saved in the
.Mx -sx
.Sx "secondary mailbox"
.Ev MBOX
when the internal variable
.Va keepsave
is set.
.El
.
.Pp
In addition to these message states, flags which otherwise have no
technical meaning in the mail system except allowing special ways of
addressing them when
.Sx "Specifying messages"
can be set on messages.
These flags are saved with messages and are thus persistent, and are
portable between a set of widely used MUAs.
.
.Bl -hang -width ".It Ic answered"
.It Ic answered
Mark messages as having been answered.
.It Ic draft
Mark messages as being a draft.
.It Ic flag
Mark messages which need special attention.
.El
.\" }}}
.
.\" .Ss "Specifying messages" {{{
.Ss "Specifying messages"
.
Commands such as
.Ic from ,
.Ic type
and
.Ic delete
can be given a list of message numbers as arguments to apply to a number
of messages at once.
Thus
.Ql delete 1 2
deletes messages 1 and 2,
whereas
.Ql delete 1-5
will delete the messages 1 through 5.
In sorted or threaded mode (see the
.Ic sort
command),
.Ql delete 1-5
will delete the messages that are located between (and including)
messages 1 through 5 in the sorted/threaded order, as shown in the
.Ic headers
summary.
The following special message names exist:
.
.
.Bl -tag -width ".It Ar BaNg"
.It Ar \&.
The current message, the so-called
.Dq dot .
.
.It Ar \&;
The message that was previously the current message.
.
.It Ar \&,
The parent message of the current message,
that is the message with the Message-ID given in the
.Ql In-Reply-To:
field or the last entry of the
.Ql References:
field of the current message.
.
.It Ar -
The next previous undeleted message,
or the next previous deleted message for the
.Ic undelete
command.
In sorted/threaded mode,
the next previous such message in the sorted/threaded order.
.
.It Ar +
The next undeleted message,
or the next deleted message for the
.Ic undelete
command.
In sorted/threaded mode,
the next such message in the sorted/threaded order.
.
.It Ar ^
The first undeleted message,
or the first deleted message for the
.Ic undelete
command.
In sorted/threaded mode,
the first such message in the sorted/threaded order.
.
.It Ar $
The last message.
In sorted/threaded mode,
the last message in the sorted/threaded order.
.
.It Ar & Ns Ar x
In threaded mode,
selects the message addressed with
.Ar x ,
where
.Ar x
is any other message specification,
and all messages from the thread that begins at it.
Otherwise it is identical to
.Ar x .
If
.Ar x
is omitted,
the thread beginning with the current message is selected.
.
.It Ar *
All messages.
.It Ar `
All messages that were included in the
.Sx "Message list arguments"
of the previous command.
.
.It Ar x-y
An inclusive range of message numbers.
Selectors that may also be used as endpoints include any of
.Ar .;-+^$ .
.
.It Ar address
A case-insensitive
.Dq any substring matches
search against the
.Ql From:
header, which will match addresses (too) even if
.Va showname
is set (and POSIX says
.Dq any address as shown in a header summary shall be matchable in this form ) ;
However, if the
.Va allnet
variable is set, only the local part of the address is evaluated
for the comparison, not ignoring case, and the setting of
.Va showname
is completely ignored.
For finer control and match boundaries use the
.Ql @
search expression.
.
.It Ar / Ns Ar string
All messages that contain
.Ar string
in the subject field (case ignored).
See also the
.Va searchheaders
variable.
If
.Ar string
is empty,
the string from the previous specification of that type is used again.
.
.It Xo Op Ar @ Ns Ar name-list Ns
.Ar @ Ns Ar expr
.Xc
All messages that contain the given case-insensitive search
.Ar expr Ns
ession; if the \*(OPal regular expression (see
.Xr re_format 7 )
support is available
.Ar expr
will be interpreted as (an extended) one if any of the
.Dq magical
(extended) regular expression characters is seen: in this case this
should match strings correctly which are in the locale
.Ev LC_CTYPE
encoding.
If the optional
.Ar @ Ns Ar name-list
part is missing, the search is restricted to the subject field body,
but otherwise
.Ar name-list
specifies a comma-separated list of header fields to search, as in
.Pp
.Dl '@to,from,cc@Someone i ought to know'
.Pp
In order to search for a string that includes a
.Ql @
(commercial at) character the
.Ar name-list
is effectively non-optional, but may be given as the empty string.
Some special header fields may be abbreviated:
.Ql f ,
.Ql t ,
.Ql c ,
.Ql b
and
.Ql s
will match
.Ql From ,
.Ql To ,
.Ql Cc ,
.Ql Bcc
and
.Ql Subject ,
respectively and case-insensitively.
The special names
.Ql header
or
.Ql <
can be used to search in (all of) the header(s) of the message, and the
special names
.Ql body
or
.Ql >
and
.Ql text
or
.Ql =
can be used to perform full text searches \(en whereas the former
searches only the body, the latter also searches the message header.
.Pp
This message specification performs full text comparison, but even with
regular expression support it is almost impossible to write a search
expression that savely matches only a specific address domain.
To request that the content of the header is treated as a list of
addresses, and to strip those down to the plain email address which the
search expression is to be matched against, prefix the header name
(abbreviation) with a tilde
.Ql ~ :
.Pp
.Dl @~f@@a\e.safe\e.domain\e.match$
.
.It Ar :c
All messages of state
.Ql c ,
where
.Ql c
is one or multiple of the following colon modifiers:
.Pp
.Bl -tag -compact -width ".It Ar :M"
.It Ar n
.Ql new
messages.
.It Ar o
Old messages (any not in state
.Ql read
or
.Ql new ) .
.It Ar u
.Ql unread
messages.
.It Ar d
.Ql deleted
messages (for the
.Ic undelete
and
.Ic from
commands only).
.It Ar r
.Ql read
messages.
.It Ar f
.Ic flag Ns
ged messages.
.It Ar a
.Ic answered
messages (cf. the variable
.Va markanswered ) .
.It Ar t
Messages marked as
.Ic draft .
.It Ar s
\*(OP Messages classified as spam (see
.Sx "Handling spam" . )
.It Ar S
\*(OP Messages with unsure spam classification.
.El
.El
.
.
.Pp
\*(OP IMAP-style SEARCH expressions may also be used.
This addressing mode is available with all types of mailbox
.Ic folder Ns
s; \*(UA will perform the search locally as necessary.
Strings must be enclosed by double quotes
.Ql \&"
in their entirety if they contain whitespace or parentheses;
within the quotes, only reverse solidus
.Ql \e
is recognized as an escape character.
All string searches are case-insensitive.
When the description indicates that the
.Dq envelope
representation of an address field is used,
this means that the search string is checked against both a list
constructed as
.
.Bd -literal -offset indent
(\*qname\*q \*qsource\*q \*qlocal-part\*q \*qdomain-part\*q)
.Ed
.
.Pp
for each address,
and the addresses without real names from the respective header field.
These search expressions can be nested using parentheses, see below for
examples.
.
.Pp
.Bl -tag -compact -width ".It Ar _n_u"
.It Ar ( criterion )
All messages that satisfy the given
.Ar criterion .
.It Ar ( criterion1 criterion2 ... criterionN )
All messages that satisfy all of the given criteria.
.
.It Ar ( or criterion1 criterion2 )
All messages that satisfy either
.Ar criterion1
or
.Ar criterion2 ,
or both.
To connect more than two criteria using
.Ql or
specifications have to be nested using additional parentheses,
as with
.Ql (or a (or b c)) ,
since
.Ql (or a b c)
really means
.Ql ((a or b) and c) .
For a simple
.Ql or
operation of independent criteria on the lowest nesting level,
it is possible to achieve similar effects by using three separate
criteria, as with
.Ql (a) (b) (c) .
.
.It Ar ( not criterion )
All messages that do not satisfy
.Ar criterion .
.It Ar ( bcc \*q Ns Ar string Ns Ar \*q )
All messages that contain
.Ar string
in the envelope representation of the
.Ql Bcc:
field.
.It Ar ( cc \*q Ns Ar string Ns Ar \*q )
All messages that contain
.Ar string
in the envelope representation of the
.Ql Cc:
field.
.It Ar ( from \*q Ns Ar string Ns Ar \*q )
All messages that contain
.Ar string
in the envelope representation of the
.Ql From:
field.
.It Ar ( subject \*q Ns Ar string Ns Ar \*q )
All messages that contain
.Ar string
in the
.Ql Subject:
field.
.It Ar ( to \*q Ns Ar string Ns Ar \*q )
All messages that contain
.Ar string
in the envelope representation of the
.Ql To:
field.
.It Ar ( header name \*q Ns Ar string Ns Ar \*q )
All messages that contain
.Ar string
in the specified
.Ql Name:
field.
.It Ar ( body \*q Ns Ar string Ns Ar \*q )
All messages that contain
.Ar string
in their body.
.It Ar ( text \*q Ns Ar string Ns Ar \*q )
All messages that contain
.Ar string
in their header or body.
.It Ar ( larger size )
All messages that are larger than
.Ar size
(in bytes).
.It Ar ( smaller size )
All messages that are smaller than
.Ar size
(in bytes).
.
.It Ar ( before date )
All messages that were received before
.Ar date ,
which must be in the form
.Ql d[d]-mon-yyyy ,
where
.Ql d
denotes the day of the month as one or two digits,
.Ql mon
is the name of the month \(en one of
.Ql Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec ,
and
.Ql yyyy
is the year as four digits, e.g.,
.Ql 28-Dec-2012 .
.
.It Ar ( on date )
All messages that were received on the specified date.
.It Ar ( since date )
All messages that were received since the specified date.
.It Ar ( sentbefore date )
All messages that were sent on the specified date.
.It Ar ( senton date )
All messages that were sent on the specified date.
.It Ar ( sentsince date )
All messages that were sent since the specified date.
.It Ar ()
The same criterion as for the previous search.
This specification cannot be used as part of another criterion.
If the previous command line contained more than one independent
criterion then the last of those criteria is used.
.El
.\" }}}
.
.\" .Ss "On terminal control and line editor" {{{
.Ss "On terminal control and line editor"
.
\*(OP Terminal control will be realized through one of the standard
.Ux
libraries, either the
.Lb libtermcap ,
or, alternatively, the
.Lb libterminfo ,
both of which will be initialized to work with the environment variable
.Ev TERM .
Terminal control will enhance or enable interactive usage aspects, e.g.,
.Sx "Coloured display" ,
and extend behaviour of the Mailx-Line-Editor (MLE), which may learn the
byte-sequences of keys like the cursor and function keys.
.
.Pp
The internal variable
.Va termcap
can be used to overwrite settings or to learn (correct(ed)) keycodes.
\*(UA may also become a fullscreen application by entering the
so-called ca-mode and switching to an alternative exclusive screen
(content) shall the terminal support it and the internal variable
.Va termcap-ca-mode
has been set explicitly.
Actual interaction with the chosen library can be disabled completely by
setting the internal variable
.Va termcap-disable ;
.Va termcap
will be queried regardless, which is true even if the \*(OPal library
support has not been enabled at configuration time as long as some other
\*(OP which (may) query terminal control sequences has been enabled.
.
.Pp
\*(OP The built-in Mailx-Line-Editor (MLE) should work in all
environments which comply to the ISO C standard
.St -isoC-amd1 ,
and will support wide glyphs if possible (the necessary functionality
had been removed from ISO C, but was included in
.St -xpg4 ) .
Prevent usage of a line editor in interactive mode by setting the
internal variable
.Va line-editor-disable .
Especially if the \*(OPal terminal control support is missing setting
entries in the internal variable
.Va termcap
will help shall the MLE misbehave, see there for more.
The MLE can support a little bit of
.Ic colour .
.
.Pp
\*(OP If the
.Ic history
feature is available then input from line editor prompts will be saved
in a history list that can be searched in and be expanded from.
Such saving can be prevented by prefixing input with any amount of
whitespace.
Aspects of history, like allowed content and maximum size, as well as
whether history shall be saved persistently, can be configured with the
internal variables
.Va history-file ,
.Va history-gabby ,
.Va history-gabby-persist
and
.Va history-size .
.
.Pp
The MLE supports a set of editing and control commands.
By default (as) many (as possible) of these will be assigned to a set of
single-letter control codes, which should work on any terminal (and can
be generated by holding the
.Dq control
key while pressing the key of desire, e.g.,
.Ql control-D ) .
If the \*(OPal
.Ic bind
command is available then the MLE commands can also be accessed freely
by assigning the command name, which is shown in parenthesis in the list
below, to any desired key-sequence, and the MLE will instead and also use
.Ic bind
to establish its built-in key bindings
(more of them if the \*(OPal terminal control is available),
an action which can then be suppressed completely by setting
.Va line-editor-no-defaults .
.Sx "Shell-style argument quoting"
notation is used in the following;
combinations not mentioned either cause job control signals or do not
generate a (unique) keycode:
.
.
.Pp
.Bl -tag -compact -width ".It Ql \eBa"
.It Ql \ecA
Go to the start of the line
.Mx
.Pf ( Cd mle-go-home ) .
.
.It Ql \ecB
Move the cursor backward one character
.Mx
.Pf ( Cd mle-go-bwd ) .
.
.It Ql \ecD
Forward delete the character under the cursor;
quits \*(UA if used on the empty line unless the internal variable
.Va ignoreeof
is set
.Mx
.Pf ( Cd mle-del-fwd ) .
.
.It Ql \ecE
Go to the end of the line
.Mx
.Pf ( Cd mle-go-end ) .
.
.It Ql \ecF
Move the cursor forward one character
.Mx
.Pf ( Cd mle-go-fwd ) .
.
.It Ql \ecG
Cancel current operation, full reset.
If there is an active history search or tabulator expansion then this
command will first reset that, reverting to the former line content;
thus a second reset is needed for a full reset in this case
.Mx
.Pf ( Cd mle-reset ) .
.
.It Ql \ecH
Backspace: backward delete one character
.Mx
.Pf ( Cd mle-del-bwd ) .
.
.It Ql \ecI
\*(NQ
Horizontal tabulator:
try to expand the word before the cursor, supporting the usual
.Sx "Filename transformations"
.Mx
.Pf ( Cd mle-complete ) .
This is affected by
.Cd mle-quote-rndtrip .
.
.It Ql \ecJ
Newline:
commit the current line
.Mx
.Pf ( Cd mle-commit ) .
.
.It Ql \ecK
Cut all characters from the cursor to the end of the line
.Mx
.Pf ( Cd mle-snarf-end ) .
.
.It Ql \ecL
Repaint the line
.Mx
.Pf ( Cd mle-repaint ) .
.
.It Ql \ecN
\*(OP Go to the next history entry
.Mx
.Pf ( Cd mle-hist-fwd ) .
.
.It Ql \ecO
(\*(OPally context-dependent) Invokes the command
.Ic dt .
.
.It Ql \ecP
\*(OP Go to the previous history entry
.Mx
.Pf ( Cd mle-hist-bwd ) .
.
.It Ql \ecQ
Toggle roundtrip mode shell quotes, where produced,
on and off
.Mx
.Pf ( Cd mle-quote-rndtrip ) .
This setting is temporary, and will be forgotten once the command line
is committed; also see
.Ic shcodec .
.
.It Ql \ecR
\*(OP Complete the current line from (the remaining) older history entries
.Mx
.Pf ( Cd mle-hist-srch-bwd ) .
.
.It Ql \ecS
\*(OP Complete the current line from (the remaining) newer history entries
.Mx
.Pf ( Cd mle-hist-srch-fwd ) .
.
.It Ql \ecT
Paste the snarf buffer
.Mx
.Pf ( Cd mle-paste ) .
.
.It Ql \ecU
The same as
.Ql \ecA
followed by
.Ql \ecK
.Mx
.Pf ( Cd mle-snarf-line ) .
.
.It Ql \ecV
Prompts for a Unicode character (its hexadecimal number) to be inserted
.Mx
.Pf ( Cd mle-prompt-char ) .
Note this command needs to be assigned to a single-letter control code
in order to become recognized and executed during input of
a key-sequence (only three single-letter control codes can be used for
that shortcut purpose); this control code is special-treated and cannot
be part of any other sequence, because any occurrence will perform the
.Cd mle-prompt-char
function immediately.
.
.It Ql \ecW
Cut the characters from the one preceding the cursor to the preceding
word boundary
.Mx
.Pf ( Cd mle-snarf-word-bwd ) .
.
.It Ql \ecX
Move the cursor forward one word boundary
.Mx
.Pf ( Cd mle-go-word-fwd ) .
.
.It Ql \ecY
Move the cursor backward one word boundary
.Mx
.Pf ( Cd mle-go-word-bwd ) .
.
.It Ql \ec[
Escape: reset a possibly used multibyte character input state machine
and \*(OPally a lingering, incomplete key binding
.Mx
.Pf ( Cd mle-cancel ) .
This command needs to be assigned to a single-letter control code in
order to become recognized and executed during input of a key-sequence
(only three single-letter control codes can be used for that shortcut
purpose).
This control code may also be part of a multi-byte sequence, but if
a sequence is active and the very control code is currently also an
expected input, then it will first be consumed by the active sequence.
.
.It Ql \ec\e
(\*(OPally context-dependent) Invokes the command
.Ql Ic z Ns + .
.
.It Ql \ec]
(\*(OPally context-dependent) Invokes the command
.Ql Ic z Ns $ .
.
.It Ql \ec^
(\*(OPally context-dependent) Invokes the command
.Ql Ic z Ns 0 .
.
.It Ql \ec_
Cut the characters from the one after the cursor to the succeeding word
boundary
.Mx
.Pf ( Cd mle-snarf-word-fwd ) .
.
.It Ql \ec?
Backspace:
.Cd mle-del-bwd .
.
.It \(en
.Mx
.Cd mle-fullreset :
different to
.Cd mle-reset
this will immediately reset a possibly active search etc.
.
.It \(en
.Mx
.Cd mle-bell :
ring the audible bell.
.El
.\" }}}
.
.\" .Ss "Coloured display" {{{
.Ss "Coloured display"
.
\*(OP \*(UA can be configured to support a coloured display and font
attributes by emitting ANSI a.k.a. ISO 6429 SGR (select graphic
rendition) escape sequences.
Usage of colours and font attributes solely depends upon the
capability of the detected terminal type that is defined by the
environment variable
.Ev TERM
and which can be fine-tuned by the user via the internal variable
.Va termcap .
.
.Pp
On top of what \*(UA knows about the terminal the boolean variable
.Va colour-pager
defines whether the actually applicable colour and font attribute
sequences should also be generated when output is going to be paged
through the external program defined by the environment variable
.Ev PAGER
(also see
.Va crt Ns
).
This is not enabled by default because different pager programs need
different command line switches or other configuration in order to
support those sequences.
\*(UA however knows about some widely used pagers and in a clean
environment it is often enough to simply set
.Va colour-pager ;
please refer to that variable for more on this topic.
.
.Pp
If the variable
.Va colour-disable
is set then any active usage of colour and font attribute sequences
is suppressed, but without affecting possibly established
.Ic colour
mappings.
.
.Pp
To define and control colours and font attributes a single multiplexer
command family exists:
.Ic colour
shows or defines colour mappings for the given colour type (e.g.,
monochrome) and
.Ic uncolour
can be used to remove mappings of a given colour type.
Since colours are only available in interactive mode, it may make
sense to conditionalize the colour setup by encapsulating it with
.Ic if :
.
.Bd -literal -offset indent
if terminal && [ "$features" =% +colour ]
  colour iso view-msginfo ft=bold,fg=green
  colour iso view-header ft=bold,fg=red from,subject
  colour iso view-header fg=red

  uncolour iso view-header from,subject
  colour iso view-header ft=bold,fg=magenta,bg=cyan
  colour 256 view-header ft=bold,fg=208,bg=230 "subject,from"
  colour mono view-header ft=bold
  colour mono view-header ft=bold,ft=reverse subject,from
endif
.Ed
.\" }}}
.
.\" .Ss "Handling spam" {{{
.Ss "Handling spam"
.
\*(OP \*(UA can make use of several spam interfaces for the purpose of
identification of, and, in general, dealing with spam messages.
A precondition of most commands in order to function is that the
.Va spam-interface
variable is set to one of the supported interfaces.
Once messages have been identified as spam their (volatile)
.Ql is-spam
state can be prompted: the
.Ql Ar :s
and
.Ql Ar :S
message specifications will address respective messages and their
.Va attrlist
entries will be used when displaying the
.Va headline
in the header display.
.
.Bl -bullet
.It
.Ic spamrate
rates the given messages and sets their
.Ql is-spam
flag accordingly.
If the spam interface offers spam scores those can also be displayed in
the header display by including the
.Ql %$
format in the
.Va headline
variable.
.It
.Ic spamham ,
.Ic spamspam
and
.Ic spamforget
will interact with the Bayesian filter of the chosen interface and learn
the given messages as
.Dq ham
or
.Dq spam ,
respectively; the last command can be used to cause
.Dq unlearning
of messages; it adheres to their current
.Ql is-spam
state and thus reverts previous teachings.
.It
.Ic spamclear
and
.Ic spamset
will simply set and clear, respectively, the mentioned volatile
.Ql is-spam
message flag, without any interface interaction.
.El
.
.Pp
The
.Xr spamassassin 1
based
.Va spam-interface
.Ql spamc
requires a running instance of the
.Xr spamd 1
server in order to function, started with the option
.Fl -allow-tell
shall Bayesian filter learning be possible.
.
.Bd -literal -offset indent
$ spamd -i localhost:2142 -i /tmp/.spamsock -d [-L] [-l]
$ spamd --listen=localhost:2142 --listen=/tmp/.spamsock \e
    --daemonize [--local] [--allow-tell]
.Ed
.
.Pp
Thereafter \*(UA can make use of these interfaces:
.
.Bd -literal -offset indent
$ \*(uA -Sspam-interface=spamc -Sspam-maxsize=500000 \e
    -Sspamc-command=/usr/local/bin/spamc \e
    -Sspamc-arguments="-U /tmp/.spamsock" -Sspamc-user=
or
$ \*(uA -Sspam-interface=spamc -Sspam-maxsize=500000 \e
    -Sspamc-command=/usr/local/bin/spamc \e
    -Sspamc-arguments="-d localhost -p 2142" -Sspamc-user=
.Ed
.
.Pp
Using the generic filter approach allows usage of programs like
.Xr bogofilter 1 .
Here is an example, requiring it to be accessible via
.Ev PATH :
.
.Bd -literal -offset indent
$ \*(uA -Sspam-interface=filter -Sspam-maxsize=500000 \e
    -Sspamfilter-ham="bogofilter -n" \e
    -Sspamfilter-noham="bogofilter -N" \e
    -Sspamfilter-nospam="bogofilter -S" \e
    -Sspamfilter-rate="bogofilter -TTu 2>/dev/null" \e
    -Sspamfilter-spam="bogofilter -s" \e
    -Sspamfilter-rate-scanscore="1;^(.+)$"
.Ed
.
.Pp
Because messages must exist on local storage in order to be scored (or
used for Bayesian filter training), it is possibly a good idea to
perform the local spam check last:
.
.Bd -literal -offset indent
define spamdelhook {
  # Server side DCC
  spamset (header x-dcc-brand-metrics "bulk")
  # Server-side spamassassin(1)
  spamset (header x-spam-flag "YES")
  del :s # TODO we HAVE to be able to do `spamrate :u ! :sS'
  move :S +maybe-spam
  spamrate :u
  del :s
  move :S +maybe-spam
}
set folder-hook-FOLDER=spamdelhook
.Ed
.
.Pp
See also the documentation for the variables
.Va spam-interface , spam-maxsize ,
.Va spamc-command , spamc-arguments , spamc-user ,
.Va spamfilter-ham , spamfilter-noham , spamfilter-nospam , \
  spamfilter-rate
and
.Va spamfilter-rate-scanscore .
.\" }}}
.
.\" }}} (DESCRIPTION)
.
.
.\" .Sh COMMANDS {{{
.Sh COMMANDS
.
Each command is typed on a line by itself,
and may take arguments following the command word.
An unquoted reverse solidus
.Ql \e
at the end of a command line
.Dq escapes
the newline character: it is discarded and the next line of input is
used as a follow-up line, with all leading whitespace removed;
once the entire command line is completed, and after removal of the
whitespace characters
.Cm space , tabulator , newline
as well as those defined by the variable
.Va ifs
from the beginning and end of the line, the processing documented in the
following begins.
Placing any whitespace characters at the beginning of a line will
prevent a possible addition of the command line to the \*(OPal
.Ic history .
.
.Pp
Apart from this generic cleanup mechanism \*(UA uses command-specific
syntax rules for command line arguments, documented in the following.
This is a completely different approach to the
.Xr sh 1 Ns
ell, which implements a standardized (programming) language, and
performs several successive transformation steps after decomposing the
given command line into tokens adhering standardized syntax guidelines.
This sometimes has side-effects for shell-style arguments, for example
.Ql \(dq$@\(dq
without positional parameters is not collapsed to nothing, as can be
seen in the example shown for the command
.Ic call .
.
.Pp
Command names may be abbreviated, in which case the first command that
matches the given prefix will be used.
The command
.Ic list
can be used to show the list of all commands, either alphabetically
sorted or in prefix search order (these do not match, also because the
POSIX standard prescribes a set of abbreviations).
\*(OPally the command
.Ic help
(or
.Ic \&? ) ,
when given an argument, will show a documentation string for the
command matching the expanded argument, as in
.Ql ?t ,
which should be a shorthand of
.Ql ?type ;
with these documentation strings both commands support a more
.Va verbose
listing mode which includes the argument type of the command and other
information which applies; a handy suggestion might thus be:
.
.Bd -literal -offset indent
? define __xv {
  # Before v15: need to enable sh(1)ell-style on _entire_ line!
  localopts 1;wysh set verbose;ignerr eval "${@}";return ${?}
}
? commandalias xv '\ecall __xv'
? xv help set
.Ed
.
.\" .Ss "Command modifiers" {{{
.Ss "Command modifiers"
.
Commands may be prefixed by one or multiple command modifiers.
.
.Bl -bullet
.It
The modifier reverse solidus
.Mx
.Cm \e ,
to be placed first, prevents
.Ic commandalias
expansions on the remains of the line, e.g.,
.Ql \eecho
will always evaluate the command
.Ic echo ,
even if an (command)alias of the same name exists.
.Ic commandalias
content may itself contain further command modifiers, including
an initial reverse solidus to prevent further expansions.
.
.It
The modifier
.Mx
.Cm ignerr
indicates that any error generated by the following command should be
ignored by the state machine and not cause a program exit with enabled
.Va errexit
or for the standardized exit cases in
.Ev POSIXLY_CORRECT
mode.
.Va \&? ,
one of the
.Sx "INTERNAL VARIABLES" ,
will be set to the real exit status of the command regardless.
.
.It
Some commands support the
.Mx
.Cm vput
modifier: if used, they expect the name of a variable, which can itself
be a variable, i.e., shell expansion is applied, as their first
argument, and will place their computation result in it instead of the
default location (it is usually written to standard output).
.Pp
The given name will be tested for being a valid
.Xr sh 1
variable name, and may therefore only consist of upper- and lowercase
characters, digits, and the underscore; the hyphen-minus may be used as
a non-portable extension; digits may not be used as first, hyphen-minus
may not be used as last characters.
In addition the name may either not be one of the known
.Sx "INTERNAL VARIABLES" ,
or must otherwise refer to a writable (non-boolean) value variable.
The actual put operation may fail nonetheless, e.g., if the variable
expects a number argument only a number will be accepted.
Any error during these operations causes the command as such to fail,
and the error number
.Va \&!
will be set to
.Va ^ERR Ns -NOTSUP ,
the exit status
.Va \&?
should be set to
.Ql -1 .
.
.It
Last, but not least, the modifier
.Mx
.Cm wysh
can be used for some old and established commands to choose the new
.Sx "Shell-style argument quoting"
rules over the traditional
.Sx "Old-style argument quoting" .
.El
.\" }}}
.
.\" .Ss "Message list arguments" {{{
.Ss "Message list arguments"
.
Some commands expect arguments that represent messages (actually
their symbolic message numbers), as has been documented above under
.Sx "Specifying messages"
already.
If no explicit message list has been specified, the next message
forward that satisfies the command's requirements will be used,
and if there are no messages forward of the current message,
the search proceeds backwards;
if there are no good messages at all to be found, an error message is
shown and the command is aborted.
.\" }}}
.
.\" .Ss "Old-style argument quoting" {{{
.Ss "Old-style argument quoting"
.
\*(ID This section documents the old, traditional style of quoting
non-message-list arguments to commands which expect this type of
arguments: whereas still used by the majority of such commands, the new
.Sx "Shell-style argument quoting"
may be available even for those via
.Cm wysh ,
one of the
.Sx "Command modifiers" .
Nonetheless care must be taken, because only new commands have been
designed with all the capabilities of the new quoting rules in mind,
which can, e.g., generate control characters.
.
.
.Bl -bullet -offset indent
.It
An argument can be enclosed between paired double-quotes
.Ql """argument"""
or
single-quotes
.Ql 'argument' ;
any whitespace, shell word expansion, or reverse solidus characters
(except as described next) within the quotes are treated literally as
part of the argument.
A double-quote will be treated literally within single-quotes and vice
versa.
Inside such a quoted string the actually used quote character can be
used nonetheless by escaping it with a reverse solidus
.Ql \e ,
as in
.Ql """y\e""ou""" .
.
.It
An argument that is not enclosed in quotes, as above, can usually still
contain space characters if those spaces are reverse solidus escaped, as in
.Ql you\e are .
.
.It
A reverse solidus outside of the enclosing quotes is discarded
and the following character is treated literally as part of the argument.
.El
.\" }}}
.
.\" .Ss "Shell-style argument quoting" {{{
.Ss "Shell-style argument quoting"
.
Commands which don't expect message-list arguments use
.Xr sh 1 Ns
ell-style, and therefore POSIX standardized, argument parsing and
quoting rules.
\*(ID Most new commands only support these new rules and are flagged
\*(NQ, some elder ones can use them with the command modifier
.Cm wysh ;
in the future only this type of argument quoting will remain.
.
.Pp
A command line is parsed from left to right and an input token is
completed whenever an unquoted, otherwise ignored, metacharacter is seen.
Metacharacters are vertical bar
.Cm \&| ,
ampersand
.Cm & ,
semicolon
.Cm \&; ,
as well as all characters from the variable
.Va ifs ,
and / or
.Cm space , tabulator , newline .
The additional metacharacters left and right parenthesis
.Cm \&( , \&)
and less-than and greater-than signs
.Cm < , >
that the
.Xr sh 1
supports are not used, and are treated as ordinary characters: for one
these characters are a vivid part of email addresses, and it seems
highly unlikely that their function will become meaningful to \*(UA.
.
.Bd -filled -offset indent
.Sy Compatibility note:
\*(ID Please note that even many new-style commands do not yet honour
.Va ifs
to parse their arguments: whereas the
.Xr sh 1 Ns
ell is a language with syntactic elements of clearly defined semantics,
\*(UA parses entire input lines and decides on a per-command base what
to do with the rest of the line.
This also means that whenever an unknown command is seen all that \*(UA
can do is cancellation of the processing of the remains of the line.
.Pp
It also often depends on an actual subcommand of a multiplexer command
how the rest of the line should be treated, and until v15 we are not
capable to perform this deep inspection of arguments.
Nonetheless, at least the following commands which work with positional
parameters fully support
.Va ifs
for an almost shell-compatible field splitting:
.Ic call , call_if , read , vpospar , xcall .
.Ed
.
.Pp
Any unquoted number sign
.Ql #
at the beginning of a new token starts a comment that extends to the end
of the line, and therefore ends argument processing.
An unquoted dollar sign
.Ql $
will cause variable expansion of the given name, which must be a valid
.Xr sh 1 Ns
ell-style variable name (see
.Cm vput ) :
.Sx "INTERNAL VARIABLES"
as well as
.Sx ENVIRONMENT
(shell) variables can be accessed through this mechanism, brace
enclosing the name is supported (i.e., to subdivide a token).
.
.Pp
Whereas the metacharacters
.Cm space , tabulator , newline
only complete an input token, vertical bar
.Cm \&| ,
ampersand
.Cm &
and semicolon
.Cm \&;
also act as control operators and perform control functions.
For now supported is semicolon
.Cm \&; ,
which terminates a single command, therefore sequencing the command line
and making the remainder of the line a subject to reevaluation.
With sequencing, multiple command argument types and quoting rules may
therefore apply to a single line, which can become problematic before
v15: e.g., the first of the following will cause surprising results.
.
.Pp
.Dl ? echo one; set verbose; echo verbose=$verbose.
.Dl ? echo one; wysh set verbose; echo verbose=$verbose.
.
.Pp
Quoting is a mechanism that will remove the special meaning of
metacharacters and reserved words, and will prevent expansion.
There are four quoting mechanisms: the escape character, single-quotes,
double-quotes and dollar-single-quotes:
.
.
.Bl -bullet -offset indent
.It
The literal value of any character can be preserved by preceding it
with the escape character reverse solidus
.Ql \e .
.
.It
Arguments which are enclosed in
.Ql 'single-\:quotes'
retain their literal value.
A single-quote cannot occur within single-quotes.
.
.It
The literal value of all characters enclosed in
.Ql \(dqdouble-\:quotes\(dq
is retained, with the exception of dollar sign
.Ql $ ,
which will cause variable expansion, as above, backquote (grave accent)
.Ql ` ,
(which not yet means anything special), reverse solidus
.Ql \e ,
which will escape any of the characters dollar sign
.Ql $
(to prevent variable expansion), backquote (grave accent)
.Ql ` ,
double-quote
.Ql \(dq
(to prevent ending the quote) and reverse solidus
.Ql \e
(to prevent escaping, i.e., to embed a reverse solidus character as-is),
but has no special meaning otherwise.
.
.It
Arguments enclosed in
.Ql $'dollar-\:single-\:quotes'
extend normal single quotes in that reverse solidus escape sequences are
expanded as follows:
.Pp
.Bl -tag -compact -width "Ql \eNNN"
.It Ql \ea
bell control character (ASCII and ISO-10646 BEL).
.It Ql \eb
backspace control characer (ASCII and ISO-10646 BS).
.It Ql \eE
escape control character (ASCII and ISO-10646 ESC).
.It Ql \ee
the same.
.It Ql \ef
form feed control character (ASCII and ISO-10646 FF).
.It Ql \en
line feed control character (ASCII and ISO-10646 LF).
.It Ql \er
carriage return control character (ASCII and ISO-10646 CR).
.It Ql \et
horizontal tabulator control character (ASCII and ISO-10646 HT).
.It Ql \ev
vertical tabulator control character (ASCII and ISO-10646 VT).
.It Ql \e\e
emits a reverse solidus character.
.It Ql \e'
single quote.
.It Ql \e"
double quote (escaping is optional).
.It Ql \eNNN
eight-bit byte with the octal value
.Ql NNN
(one to three octal digits), optionally prefixed by an additional
.Ql 0 .
A 0 byte will suppress further output for the quoted argument.
.It Ql \exHH
eight-bit byte with the hexadecimal value
.Ql HH
(one or two hexadecimal characters).
A 0 byte will suppress further output for the quoted argument.
.It Ql \eUHHHHHHHH
the Unicode / ISO-10646 character with the hexadecimal codepoint value
.Ql HHHHHHHH
(one to eight hexadecimal digits) \(em note that Unicode defines the
maximum codepoint ever to be supported as
.Ql 0x10FFFF
(in planes of
.Ql 0xFFFF
characters each).
This escape is only supported in locales that support Unicode (see
.Sx "Character sets" ) ,
in other cases the sequence will remain unexpanded unless the given code
point is ASCII compatible or (if the \*(OPal character set conversion is
available) can be represented in the current locale.
The character NUL will suppress further output for the quoted argument.
.It Ql \euHHHH
Identical to
.Ql \eUHHHHHHHH
except it takes only one to four hexadecimal digits.
.It Ql \ecX
Emits the non-printable (ASCII and compatible) C0 control codes
0 (NUL) to 31 (US), and 127 (DEL).
Printable representations of ASCII control codes can be created by
mapping them to a different part of the ASCII character set, which is
possible by adding the number 64 for the codes 0 to 31, e.g., 7 (BEL) is
.Ql 7 + 64 = 71 = G .
The real operation is a bitwise logical XOR with 64 (bit 7 set, see
.Ic vexpr ) ,
thus also covering code 127 (DEL), which is mapped to 63 (question mark):
.Ql ? vexpr ^ 127 64 .
.Pp
Whereas historically circumflex notation has often been used for
visualization purposes of control codes, e.g.,
.Ql ^G ,
the reverse solidus notation has been standardized:
.Ql \ecG .
Some control codes also have standardized (ISO-10646, ISO C) aliases,
as shown above (e.g.,
.Ql \ea ,
.Ql \en ,
.Ql \et ) :
whenever such an alias exists it will be used for display purposes.
The control code NUL
.Pf ( Ql \ec@ ,
a non-standard extension) will suppress further output for the remains
of the token (which may extend beyond the current quote), or, depending
on the context, the remains of all arguments for the current command.
.It Ql \e$NAME
Non-standard extension: expand the given variable name, as above.
Brace enclosing the name is supported.
.It Ql \e`{command}
Not yet supported, just to raise awareness: Non-standard extension.
.El
.El
.
.Pp
Caveats:
.
.Bd -literal -offset indent
? echo 'Quotes '${HOME}' and 'tokens" differ!"# no comment
? echo Quotes ${HOME} and tokens differ! # comment
? echo Don"'"t you worry$'\ex21' The sun shines on us. $'\eu263A'
.Ed
.\" }}}
.
.\" .Ss "Raw data arguments for codec commands" {{{
.Ss "Raw data arguments for codec commands"
.
A special set of commands, which all have the string
.Dq codec
in their name, e.g.,
.Ic addrcodec ,
.Ic shcodec ,
.Ic urlcodec ,
take raw string data as input, which means that the content of the
command input line is passed completely unexpanded and otherwise
unchanged: like this the effect of the actual codec is visible without
any noise of possible shell quoting rules etc., i.e., the user can input
one-to-one the desired or questionable data.
To gain a level of expansion, the entire command line can be
.Ic eval Ns
uated first, e.g.,
.
.Bd -literal -offset indent
? vput shcodec res encode /usr/Sch\[:o]nes Wetter/heute.txt
? echo $res
$'/usr/Sch\eu00F6nes Wetter/heute.txt'
? shcodec d $res
$'/usr/Sch\eu00F6nes Wetter/heute.txt'
? eval shcodec d $res
/usr/Sch\[:o]nes Wetter/heute.txt
.Ed
.\" }}}
.
.\" .Ss "Filename transformations" {{{
.Ss "Filename transformations"
.
Filenames, where expected, and unless documented otherwise, are
subsequently subject to the following filename transformations, in
sequence:
.
.Bl -bullet -offset indent
.It
If the given name is a registered
.Ic shortcut ,
it will be replaced with the expanded shortcut.
.
.It
The filename is matched against the following patterns or strings:
.Pp
.Bl -hang -compact -width ".Ar %user"
.It Ar #
(Number sign) is expanded to the previous file.
.It Ar %
(Percent sign) is replaced by the invoking
.Mx -ix "primary system mailbox"
user's primary system mailbox, which either is the (itself expandable)
.Va inbox
if that is set, the standardized absolute pathname indicated by
.Ev MAIL
if that is set, or a built-in compile-time default otherwise.
.It Ar %user
Expands to the primary system mailbox of
.Ar user
(and never the value of
.Va inbox ,
regardless of its actual setting).
.It Ar &
(Ampersand) is replaced with the invoking users
.Mx -ix "secondary mailbox"
secondary mailbox, the
.Ev MBOX .
.It Ar +file
Refers to a
.Ar file
in the
.Va folder
directory (if that variable is set).
.It Ar %:filespec
Expands to the same value as
.Ar filespec ,
but has special meaning when used with, e.g., the command
.Ic file :
the file will be treated as a primary system mailbox by, e.g., the
.Ic mbox
and
.Ic save
commands, meaning that messages that have been read in the current
session will be moved to the
.Ev MBOX
mailbox instead of simply being flagged as read.
.El
.
.It
Meta expansions are applied to the resulting filename, as applicable to
the resulting file access protocol (also see
.Sx "On URL syntax and credential lookup" ) .
If the fully expanded filename results in multiple pathnames and the
command is expecting only one file, an error results.
.Pp
For the file-protocol, a leading tilde
.Ql ~
character will be replaced by the expansion of
.Ev HOME ,
except when followed by a valid user name, in which case the home
directory of the given user is used instead.
.Pp
In addition a shell expansion as if specified in double-quotes (see
.Sx "Shell-style argument quoting" )
is applied, so that any occurrence of
.Ql $VARIABLE
(or
.Ql ${VARIABLE} )
will be replaced by the expansion of the variable, if possible;
.Sx "INTERNAL VARIABLES"
as well as
.Sx ENVIRONMENT
(shell) variables can be accessed through this mechanism.
.Pp
In interactive context, in order to allow simple value acceptance (via
.Dq ENTER ) ,
arguments will usually be displayed in a properly quoted form, e.g., a file
.Ql diet\e is \ecurd.txt
may be displayed as
.Ql 'diet\e is \ecurd.txt' .
.El
.\" }}}
.
.\" .Ss "Commands" {{{
.Ss "Commands"
.
The following commands are available:
.
.Bl -tag -width ".It Ic BaNg"
.
.
.Mx
.It Ic \&!
Executes the
.Ev SHELL
command which follows, replacing unescaped exclamation marks with the
previously executed command if the internal variable
.Va bang
is set.
This command supports
.Cm vput
as documented in
.Sx "Command modifiers" ,
and manages the error number
.Va \&! .
A 0 or positive exit status
.Va \&?
reflects the exit status of the command, negative ones that
an error happened before the command was executed, or that the program
did not exit cleanly, but, e.g., due to a signal: the error number is
.Va ^ERR Ns -CHILD ,
then.
.
.Pp
In conjunction with the
.Cm vput
modifier the following special cases exist:
a negative exit status occurs if the collected data could not be stored
in the given variable, which is a
.Va ^ERR Ns -NOTSUP
error that should otherwise not occur.
.Va ^ERR Ns -CANCELED
indicates that no temporary file could be created to collect the command
output at first glance.
In case of catchable out-of-memory situations
.Va ^ERR Ns -NOMEM
will occur and \*(UA will try to store the empty string, just like with
all other detected error conditions.
.
.
.Mx
.It Ic #
The comment-command causes the entire line to be ignored.
.Sy Note:
this really is a normal command which' purpose is to discard its
arguments, not a
.Dq comment-start
indicating special character, which means that, e.g., trailing comments
on a line are not possible.
.
.Mx
.It Ic +
Goes to the next message in sequence and types it
(like
.Dq ENTER ) .
.
.Mx
.It Ic -
Display the preceding message, or the n'th previous message if given
a numeric argument n.
.
.Mx
.It Ic =
Show the current message number (the
.Dq dot ) .
.
.Mx
.It Ic \&?
Show a brief summary of commands.
\*(OP Given an argument a synopsis for the command in question is
shown instead; commands can be abbreviated in general and this command
can be used to see the full expansion of an abbreviation including the
synopsis, try, e.g.,
.Ql ?h ,
.Ql ?hel
and
.Ql ?help
and see how the output changes.
This mode also supports a more
.Va verbose
output, which will provide the informations documented for
.Ic list .
.
.Mx
.It Ic \&|
A synonym for the
.Ic pipe
command.
.
.Mx
.Mx
.It Ic account , unaccount
(ac, una) Creates, selects or lists (an) account(s).
Accounts are special incarnations of
.Ic define Ns d
macros and group commands and variable settings which together usually
arrange the environment for the purpose of creating an email account.
Different to normal macros settings which are covered by
.Ic localopts
\(en here by default enabled! \(en will not be reverted before the
.Ic account
is changed again.
The special account
.Ql null
(case-insensitive) always exists, and all but it can be deleted by the
latter command, and in one operation with the special name
.Ql * .
.Pp
Without arguments a listing of all defined accounts is shown.
With one argument the given account is activated: the system
.Va inbox
of that account will be activated (as via
.Ic file ) ,
a possibly installed
.Va folder-hook
will be run, and the internal variable
.Va account
will be updated.
The two argument form is identical to defining a macro as via
.Ic define :
.Bd -literal -offset indent
account myisp {
  set folder=~/mail inbox=+syste.mbox record=+sent.mbox
  set from='(My Name) myname@myisp.example'
  set mta=smtp://mylogin@smtp.myisp.example
}
.Ed
.
.
.Mx
.It Ic addrcodec
Perform email address codec transformations on raw-data argument, rather
according to email standards (RFC 5322; \*(ID will furtherly improve).
Supports
.Cm vput
(see
.Sx "Command modifiers" ) ,
and manages the error number
.Va \&! .
The first argument must be either
.Ar [+[+[+]]]e[ncode] ,
.Ar d[ecode]
or
.Ar s[kin] ,
and specifies the operation to perform on the rest of the line.
.
.Pp
Decoding will show how a standard-compliant MUA will display the given
argument, which should be an email address.
Please be aware that most MUAs have difficulties with the address
standards, and vary wildly when (comments) in parenthesis,
.Dq double-quoted
strings, or quoted-pairs, as below, become involved.
\*(ID \*(UA currently does not perform decoding when displaying addresses.
.
.Pp
Skinning is identical to decoding but only outputs the plain address,
without any string, comment etc. components.
Another difference is that it may fail with the error number
.Va \&!
set to
.Va ^ERR Ns -INVAL
if decoding fails to find a(n) (valid) email address, in which case the
unmodified input will be output again.
.
.Pp
Encoding supports four different modes, lesser automated versions can be
chosen by prefixing one, two or three plus signs: the standard imposes
a special meaning on some characters, which thus have to be transformed
to so-called quoted-pairs by pairing them with a reverse solidus
.Ql \e
in order to remove the special meaning; this might change interpretation
of the entire argument from what has been desired, however!
Specify one plus sign to remark that parenthesis shall be left alone,
two for not turning double quotation marks into quoted-pairs, and three
for also leaving any user-specified reverse solidus alone.
The result will always be valid, if a successful exit status is reported.
\*(ID Addresses need to be specified in between angle brackets
.Ql < ,
.Ql >
if the construct becomes more difficult, otherwise the current parser
will fail; it is not smart enough to guess right.
.
.Bd -literal -offset indent
? addrc enc "Hey, you",<diet@exam.ple>\e out\e there
"\e"Hey, you\e", \e\e out\e\e there" <diet@exam.ple>
? addrc d "\e"Hey, you\e", \e\e out\e\e there" <diet@exam.ple>
"Hey, you", \e out\e there <diet@exam.ple>
? addrc s "\e"Hey, you\e", \e\e out\e\e there" <diet@exam.ple>
diet@exam.ple
.Ed
.
.
.Mx
.Mx
.It Ic alias , unalias
(a, una) Aliases are a method of creating personal distribution lists
that map a single alias name to none to multiple real receivers;
these aliases become expanded after message composing is completed.
The latter command removes the given list of aliases, the special name
.Ql *
will discard all existing aliases.
The former command shows all currently defined aliases when used without
arguments, and with one argument the expansion of the given alias.
With more than one argument, creates or appends to the alias name given
as the first argument the remaining arguments.
Alias names are restricted to alphabetic characters, digits, the
underscore, hyphen-minus, the number sign, colon, commercial at and
period, the last character can also be the dollar sign:
.Ql [[:alnum:]_#:@.-]+$? .
.
.Mx
.Mx
.It Ic alternates , unalternates
\*(NQ (alt) Manage a list of alternate addresses or names of the active user,
members of which will be removed from recipient lists.
The latter command removes the given list of alternates, the special name
.Ql *
will discard all existing aliases.
The former command manages the error number
.Va \&!
and shows the current set of alternates when used without arguments; in
this mode it supports
.Cm vput
(see
.Sx "Command modifiers" ) .
Otherwise the given arguments (after being checked for validity) are
appended to the list of alternate names; in
.Va posix
mode they replace that list instead.
There is a set of implicit alternates which is formed of the values of
.Ev LOGNAME ,
.Va from ,
.Va sender
and
.Va replyto .
.
.Mx
.Mx
.It Ic answered , unanswered
Take a message lists and mark each message as having been answered,
having not been answered, respectively.
Messages will be marked answered when being
.Ic reply Ns d
to automatically if the
.Va markanswered
variable is set.
See the section
.Sx "Message states" .
.
.
.Mx
.Mx
.It Ic bind , unbind
\*(OP\*(NQ The bind command extends the MLE (see
.Sx "On terminal control and line editor" )
with freely configurable key bindings.
The latter command removes from the given context the given key binding,
both of which may be specified as a wildcard
.Ql * ,
so that, e.g.,
.Ql unbind * *
will remove all bindings of all contexts.
Due to initialization order unbinding will not work for built-in key
bindings upon program startup, however: please use
.Va line-editor-no-defaults
for this purpose instead.
.
.Pp
With one argument the former command shows all key bindings for the
given context, specifying an asterisk
.Ql *
will show the bindings of all contexts; a more verbose listing will be
produced if either of
.Va debug
or
.Va verbose
are set.
With two or more arguments a binding is (re)established:
the first argument is the context to which the binding shall apply,
the second argument is a comma-separated list of the
.Dq keys
which form the binding, and any remaining arguments form the expansion.
To indicate that a binding shall not be auto-committed, but that the
expansion shall instead be furtherly editable by the user, a commercial at
.Ql @
(that will be removed) can be placed last in the expansion, from which
leading and trailing whitespace will finally be removed.
Reverse solidus cannot be used as the last character of expansion.
.
.Pp
Contexts define when a binding applies, i.e., a binding will not be seen
unless the context for which it is defined for is currently active.
This is not true for the shared binding
.Ql base ,
which is the foundation for all other bindings and as such always
applies, its bindings, however, only apply secondarily.
The available contexts are the shared
.Ql base ,
the
.Ql default
context which is used in all not otherwise documented situations, and
.Ql compose ,
which applies to compose mode only.
.
.Pp
.Dq Keys
which form the binding are specified as a comma-separated list of
byte-sequences, where each list entry corresponds to one key(press).
A list entry may, indicated by a leading colon character
.Ql \&: ,
also refer to the name of a terminal capability; several dozen names
will be compiled in and may be specified either by their
.Xr terminfo 5 ,
or, if existing, by their
.Xr termcap 5
name, regardless of the actually used \*(OPal terminal control library.
It is possible to use any capability, as long as the name is resolvable
by the \*(OPal control library or was defined via the internal variable
.Va termcap .
Input sequences are not case-normalized, so that an exact match is
required to update or remove a binding.
Examples:
.
.Bd -literal -offset indent
? bind base $'\eE',d mle-snarf-word-fwd # Esc(ape)
? bind base $'\eE',$'\ec?' mle-snarf-word-bwd # Esc, Delete
? bind default $'\ecA',:khome,w 'echo An editable binding@'
? bind default a,b,c rm -irf / @  # Another editable binding
? bind default :kf1 File %
? bind compose :kf1 ~e
.Ed
.
.Pp
Note that the entire comma-separated list is first parsed (over) as a
shell-token with whitespace as the field separator, before being parsed
and expanded for real with comma as the field separator, therefore
whitespace needs to be properly quoted, see
.Sx "Shell-style argument quoting" .
Using Unicode reverse solidus escape sequences renders a binding
defunctional if the locale does not support Unicode (see
.Sx "Character sets" ) ,
and using terminal capabilities does so if no (corresponding) terminal
control support is (currently) available.
.
.Pp
The following terminal capability names are built-in and can be used in
.Xr terminfo 5
or (if available) the two-letter
.Xr termcap 5
notation.
See the respective manual for a list of capabilities.
The program
.Xr infocmp 1
can be used to show all the capabilities of
.Ev TERM
or the given terminal type;
using the
.Fl \&\&x
flag will also show supported (non-standard) extensions.
.
.Pp
.Bl -tag -compact -width kcuuf_or_kcuuf
.It Cd kbs Ns \0or Cd kb
Backspace.
.It Cd kdch1 Ns \0or Cd kD
Delete character.
.It Cd kDC Ns \0or Cd *4
\(em shifted variant.
.It Cd kel Ns \0or Cd kE
Clear to end of line.
.It Cd kext Ns \0or Cd @9
Exit.
.It Cd kich1 Ns \0or Cd kI
Insert character.
.It Cd kIC Ns \0or Cd #3
\(em shifted variant.
.It Cd khome Ns \0or Cd kh
Home.
.It Cd kHOM Ns \0or Cd #2
\(em shifted variant.
.It Cd kend Ns \0or Cd @7
End.
.It Cd knp Ns \0or Cd kN
Next page.
.It Cd kpp Ns \0or Cd kP
Previous page.
.It Cd kcub1 Ns \0or Cd kl
Left cursor (with more modifiers: see below).
.It Cd kLFT Ns \0or Cd #4
\(em shifted variant.
.It Cd kcuf1 Ns \0or Cd kr
Right cursor (ditto).
.It Cd kRIT Ns \0or Cd %i
\(em shifted variant.
.It Cd kcud1 Ns \0or Cd kd
Down cursor (ditto).
.It Cd kDN
\(em shifted variant (only terminfo).
.It Cd kcuu1 Ns \0or Cd ku
Up cursor (ditto).
.It Cd kUP
\(em shifted variant (only terminfo).
.It Cd kf0 Ns \0or Cd k0
Function key 0.
Add one for each function key up to
.Cd kf9
and
.Cd k9 ,
respectively.
.It Cd kf10 Ns \0or Cd k;
Function key 10.
.It Cd kf11 Ns \0or Cd F1
Function key 11.
Add one for each function key up to
.Cd kf19
and
.Cd F9 ,
respectively.
.El
.
.Pp
Some terminals support key-modifier combination extensions, e.g.,
.Ql Alt+Shift+xy .
For example, the delete key,
.Cd kdch1 :
in its shifted variant, the name is mutated to
.Cd  kDC ,
then a number is appended for the states
.Ql Alt
.Pf ( Cd kDC3 ) ,
.Ql Shift+Alt
.Pf ( Cd kDC4 ) ,
.Ql Control
.Pf ( Cd kDC5 ) ,
.Ql Shift+Control
.Pf ( Cd kDC6 ) ,
.Ql Alt+Control
.Pf ( Cd kDC7 ) ,
finally
.Ql Shift+Alt+Control
.Pf ( Cd kDC8 ) .
The same for the left cursor key,
.Cd kcub1 :
.Cd KLFT , KLFT3 , KLFT4 , KLFT5 , KLFT6 , KLFT7 , KLFT8 .
.
.Pp
It is advisable to use an initial escape or other control character (e.g.,
.Ql \ecA )
for bindings which describe user key combinations (as opposed to purely
terminal capability based ones), in order to avoid ambiguities whether
input belongs to key sequences or not; it also reduces search time.
Adjusting
.Va bind-timeout
may help shall keys and sequences be falsely recognized.
.
.
.Mx
.It Ic call
\*(NQ Calls the given macro, which must have been created via
.Ic define ,
otherwise a
.Va ^ERR Ns -NOENT
error occurs.
Parameters given to macros are implicitly local to the macro's scope, and
may be accessed via special (positional) parameters, e.g.,
.Va 1 ,
.Va * ,
.Va @ ,
.Va # .
The positional parameters may be removed by
.Ic shift Ns
ing them off the stack (exceeding the supported number of arguments
results in a
.Va ^ERR Ns -OVERFLOW ) ,
and are otherwise controllable via
.Ic vpospar .
Changes to other
.Sx ENVIRONMENT
as well as
.Sx "INTERNAL VARIABLES"
can be reverted before the current level regains control by setting
.Ic localopts
for called macro(s) (or in them, of course).
Macro execution can be terminated at any time by calling
.Ic return .
.
.Pp
Calling macros recursively will at some time excess the stack size
limit, causing a hard program abortion; if recursively calling a macro
is the last command of the current macro, consider to use the command
.Ic xcall ,
which will first release all resources of the current macro before
replacing the current macro with the called one.
Numeric and string operations can be performed via
.Ic vexpr ,
and
.Ic eval
may be helpful to recreate argument lists.
.
.Bd -literal -offset indent
define exmac {
  echo Parameter 1 of ${#} is ${1}, all: ${*} / ${@}
  return 1000 0
}
call exmac Hello macro exmac!
.Ed
.
.Pp
Caveats: \*(UA parses  entire input lines and decides on a per-command
base what to do with the rest of the line, different to the
.Xr sh 1 Ns
ell, which implements a standardized (programming) language, and
performs several successive transformation steps after decomposing the
given command line into tokens adhering standardized syntax guidelines.
E.g., in the following code snippets of otherwise identical meaning,
a shell will see zero arguments, whereas \*(UA sees one, unless an
additional expansion (via
.Ic eval )
is explicitly used:
.
.Bd -literal -offset indent
$ cat > t.sh << '___'; cat > t.rc << '___'
x() { echo $#; }
set --
x "$@"
___
define x {
  echo $#
}
vpospar set
call x "$@"
eval call x "$@"
___
$ sh t.sh; \*(uA -X'source t.rc' -Xx
0
1
0
.Ed
.
.
.Mx
.It Ic call_if
Identical to
.Ic call
if the given macro has been created via
.Ic define ,
but doesn't fail nor warn if the macro doesn't exist.
.
.Mx
.It Ic cd
(ch) Change the working directory to
.Ev HOME
or the given argument.
Synonym for
.Ic chdir .
.
.Mx
.It Ic certsave
\*(OP Only applicable to S/MIME signed messages.
Takes a message list and a filename and saves the certificates
contained within the message signatures to the named file in both
human-readable and PEM format.
The certificates can later be used to send encrypted messages to the
respective message senders by setting
.Va smime-encrypt-USER@HOST
variables.
.
.Mx
.Mx
.It Ic charsetalias , uncharsetalias
\*(NQ Manage (character set conversion) character set alias mappings,
as documented in the section
.Sx "Character sets" .
Character set aliases are expanded recursively, but no expansion is
performed on values of the user-settable variables, e.g.,
.Va charset-8bit .
These are effectively no-operations if character set conversion
is not available (i.e., no
.Ql +iconv
in
.Va features ) .
Without arguments the list of all currently defined aliases is shown,
with one argument the expansion of the given alias.
Otherwise all given arguments are treated as pairs of character sets and
their desired target alias name, creating new or changing already
existing aliases, as necessary.
.Pp
The latter deletes all aliases given as arguments, the special argument
.Ql *
will remove all aliases.
.
.Mx
.It Ic chdir
(ch) Change the working directory to
.Ev HOME
or the given argument.
Synonym for
.Ic cd .
.
.Mx
.Mx
.It Ic collapse , uncollapse
Only applicable to threaded mode.
Takes a message list and makes all replies to these messages invisible
in header summaries, except for
.Ql new
messages and the
.Dq dot .
Also when a message with collapsed replies is displayed,
all of these are automatically uncollapsed.
The latter command undoes collapsing.
.
.
.Mx
.Mx
.It Ic colour , uncolour
\*(OP\*(NQ Manage colour mappings of and for a
.Sx "Coloured display" .
The type of colour is given as the (case-insensitive) first argument,
which must be one of
.Ql 256
for 256-colour terminals,
.Ql 8 ,
.Ql ansi
or
.Ql iso
for the standard 8-colour ANSI / ISO 6429 color palette and
.Ql 1
or
.Ql mono
for monochrome terminals.
Monochrome terminals cannot deal with colours, but only (some) font
attributes.
.
.Pp
Without further arguments the list of all currently defined mappings
for the given colour type is shown (as a special case giving
.Ql all
or
.Ql *
will show the mappings of all types).
Otherwise the second argument defines the mappable slot, and the third
argument a (comma-separated list of) colour and font attribute
specification(s), and the optional fourth argument can be used to
specify a precondition: if conditioned mappings exist they are tested in
(creation) order unless a (case-insensitive) match has been found, and
the default mapping (if any has been established) will only be chosen as
a last resort.
The types of precondition available depend on the mappable slot (see
.Sx "Coloured display"
for some examples), the following of which exist:
.
.Pp
Mappings prefixed with
.Ql mle-
are used for the \*(OPal built-in Mailx-Line-Editor (MLE, see
.Sx "On terminal control and line editor" )
and do not support preconditions.
.Pp
.Bl -tag -compact -width view-partinfo
.It Ar mle-position
This mapping is used for the position indicator that is visible when
a line cannot be fully displayed on the screen.
.It Ar mle-prompt
Used for the
.Va prompt .
.El
.
.Pp
Mappings prefixed with
.Ql sum-
are used in header summaries, and they all understand the preconditions
.Ql dot
(the current message) and
.Ql older
for elder messages (only honoured in conjunction with
.Va datefield-markout-older ) .
.Pp
.Bl -tag -compact -width view-partinfo
.It Ar sum-dotmark
This mapping is used for the
.Dq dotmark
that can be created with the
.Ql %>
or
.Ql %<
formats of the variable
.Va headline .
.It Ar sum-header
For the complete header summary line except the
.Dq dotmark
and the thread structure.
.It Ar sum-thread
For the thread structure which can be created with the
.Ql %i
format of the variable
.Va headline .
.El
.
.Pp
Mappings prefixed with
.Ql view-
are used when displaying messages.
.Pp
.Bl -tag -compact -width view-partinfo
.It Ar view-from_
This mapping is used for so-called
.Ql From_
lines, which are MBOX file format specific header lines.
.It Ar view-header
For header lines.
A comma-separated list of headers to which the mapping applies may be
given as a precondition; if the \*(OPal regular expression support is
available then if any of the
.Dq magical
(extended) regular expression characters is seen the precondition will
be evaluated as (an extended) one.
.It Ar view-msginfo
For the introductional message info line.
.It Ar view-partinfo
For MIME part info lines.
.El
.
.Pp
The following (case-insensitive) colour definitions and font attributes
are understood, multiple of which can be specified in a comma-separated
list:
.
.Bl -tag -width ft=
.It Ar ft=
a font attribute:
.Ql bold ,
.Ql reverse
or
.Ql underline .
It is possible (and often applicable) to specify multiple font
attributes for a single mapping.
.
.It Ar fg=
foreground colour attribute:
.Ql black ,
.Ql blue ,
.Ql green ,
.Ql red ,
.Ql brown ,
.Ql magenta ,
.Ql cyan
or
.Ql white .
To specify a 256-color mode a decimal number colour specification in
the range 0 to 255, inclusive, is supported, and interpreted as follows:
.Pp
.Bl -tag -compact -width "999 - 999"
.It 0 - 7
the standard ISO 6429 colors, as above.
.It 8 - 15
high intensity variants of the standard colors.
.It 16 - 231
216 colors in tuples of 6.
.It 232 - 255
grayscale from black to white in 24 steps.
.El
.Bd -literal -offset indent
#!/bin/sh -
fg() { printf "\e033[38;5;${1}m($1)"; }
bg() { printf "\e033[48;5;${1}m($1)"; }
i=0
while [ $i -lt 256 ]; do fg $i; i=$(($i + 1)); done
printf "\e033[0m\en"
i=0
while [ $i -lt 256 ]; do bg $i; i=$(($i + 1)); done
printf "\e033[0m\en"
.Ed
.
.It Ar bg=
background colour attribute (see
.Cd fg=
for possible values).
.El
.
.Pp
The command
.Ic \&uncolour
will remove for the given colour type (the special type
.Ql *
selects all) the given mapping; if the optional precondition argument is
given only the exact tuple of mapping and precondition is removed.
The special name
.Ql *
will remove all mappings (no precondition allowed), thus
.Ql uncolour * *
will remove all established mappings.
.
.
.Mx
.Mx
.It Ic commandalias , uncommandalias
\*(NQ Define or list, and remove, respectively, command aliases.
An (command)alias can be used everywhere a normal command can be used,
but always takes precedence: any arguments that are given to the command
alias are joined onto the alias expansion, and the resulting string
forms the command line that is, in effect, executed.
The latter command removes all given aliases, the special name
.Ql *
will remove all existing aliases.
When used without arguments the former shows a list of all currently
known aliases, with one argument only the expansion of the given one.
.Pp
With two or more arguments a command alias is defined or updated: the
first argument is the name under which the remaining command line should
be accessible, the content of which can be just about anything.
An alias may itself expand to another alias, but to avoid expansion loops
further expansion will be prevented if an alias refers to itself or if
an expansion depth limit is reached.
Explicit expansion prevention is available via reverse solidus
.Cm \e ,
one of the
.Sx "Command modifiers" .
.Bd -literal -offset indent
? commandalias xx
\*(uA: `commandalias': no such alias: xx
? commandalias xx echo hello,
? commandalias xx
commandalias xx 'echo hello,'
? xx
hello,
? xx world
hello, world
.Ed
.
.Mx
.It Ic Copy
(C) Copy messages to files whose names are derived from the author of
the respective message and do not mark them as being saved;
otherwise identical to
.Ic Save .
.
.Mx
.It Ic copy
(c) Copy messages to the named file and do not mark them as being saved;
otherwise identical to
.Ic save .
.
.Mx
.It Ic cwd
Show the name of the current working directory, as reported by
.Xr getcwd 3 .
Supports
.Cm vput
(see
.Sx "Command modifiers" ) .
The return status is tracked via
.Va \&! .
.
.Mx
.It Ic Decrypt
\*(OP For unencrypted messages this command is identical to
.Ic Copy ;
Encrypted messages are first decrypted, if possible, and then copied.
.
.Mx
.It Ic decrypt
\*(OP For unencrypted messages this command is identical to
.Ic copy ;
Encrypted messages are first decrypted, if possible, and then copied.
.
.Mx
.Mx
.It Ic define , undefine
Without arguments the current list of macros, including their content,
is shown, otherwise a macro is defined, replacing an existing macro of
the same name.
A macro definition is a sequence of commands in the following form:
.Bd -literal -offset indent
define name {
  command1
  command2
  ...
  commandN
}
.Ed
.Pp
A defined macro can be invoked explicitly by using the
.Ic call ,
.Ic call_if
and
.Ic xcall
commands, or implicitly if a macro hook is triggered, e.g., a
.Va folder-hook .
It is possible to localize adjustments, like creation, deletion and
modification of
.Sx "INTERNAL VARIABLES" ,
by using the
.Ic localopts
command; the scope which is localized depends on how (i.e.,
.Dq as what :
normal macro, folder hook, hook,
.Ic account
switch) the macro is invoked.
Execution of a macro body can be stopped from within by calling
.Ic return .
Inside a
.Ic call Ns
ed macro, given positional parameters can be
.Ic shift Ns
ed, or become completely replaced, removed etc. via
.Ic vpospar .
.Pp
The latter command deletes the given macro, the special name
.Ql *
will discard all existing macros.
Creation and deletion of (a) macro(s) can be performed from within
a running macro.
.
.Mx
.Mx
.It Ic delete , undelete
(d, u) Marks the given message list as being or not being
.Ql deleted ,
respectively; if no argument has been specified then the usual search
for a visible message is performed, as documented for
.Sx "Message list arguments" ,
showing only the next input prompt if the search fails.
Deleted messages will neither be saved in the
.Mx -sx
.Sx "secondary mailbox"
.Ev MBOX
nor will they be available for most other commands.
If the
.Va autoprint
variable is set, the new
.Dq dot
or the last message restored, respectively, is automatically
.Ic type Ns
d; also see
.Ic dp ,
.Ic dt .
.
.Mx
.It Ic discard
(di) Identical to
.Ic ignore .
Superseded by the multiplexer
.Ic headerpick .
.
.Mx
.Mx
.It Ic dp , dt
Delete the given messages and automatically
.Ic type
the new
.Dq dot
if one exists, regardless of the setting of
.Va autoprint .
.
.Mx
.It Ic dotmove
Move the
.Dq dot
up or down by one message when given
.Ql +
or
.Ql -
argument, respectively.
.
.Mx
.Mx
.It Ic draft , undraft
Take message lists and mark each given message as being draft, or not
being draft, respectively, as documented in the section
.Sx "Message states" .
.
.Mx
.It Ic echo
\*(NQ (ec) Echoes arguments to standard output and writes a trailing
newline, whereas the otherwise identical
.Ic echon
does not.
.Sx "Shell-style argument quoting"
is used,
.Sx "Filename transformations"
are applied to the expanded arguments.
.
.Mx
.It Ic echoerr
\*(NQ Identical to
.Ic echo
except that is echoes to standard error.
Also see
.Ic echoerrn .
In interactive sessions the \*(OPal message ring queue for
.Ic errors
will be used instead, if available.
.
.Mx
.It Ic echon
\*(NQ Identical to
.Ic echo ,
but does not write a trailing newline.
.
.Mx
.It Ic echoerrn
\*(NQ Identical to
.Ic echoerr ,
but does not write a trailing newline.
.
.Mx
.It Ic edit
(e) Point the text editor (as defined in
.Ev EDITOR )
at each message from the given list in turn.
Modified contents are discarded unless the
.Va writebackedited
variable is set, and are not used unless the mailbox can be written to
and the editor returns a successful exit status.
.
.Mx
.It Ic elif
Part of the
.Ic if Ns \0/\: Ic elif Ns \0/\: Ic else Ns \0/\: Ic endif
conditional \(em if the condition of a preceding
.Ic if
was false, check the following condition and execute the following block
if it evaluates true.
.
.Mx
.It Ic else
(el) Part of the
.Ic if Ns \0/\: Ic elif Ns \0/\: Ic else Ns \0/\: Ic endif
conditional \(em if none of the conditions of the preceding
.Ic if
and
.Ic elif
commands was true, the
.Ic else
block is executed.
.
.Mx
.It Ic endif
(en) Marks the end of an
.Ic if Ns \0/\: Ic elif Ns \0/\: Ic else Ns \0/\: Ic endif
conditional execution block.
.
.
.Mx
.It Ic environ
\*(NQ \*(UA has a strict notion about which variables are
.Sx "INTERNAL VARIABLES"
and which are managed in the program
.Sx ENVIRONMENT .
Since some of the latter are a vivid part of \*(UAs functioning,
however, they are transparently integrated into the normal handling of
internal variables via
.Ic set
and
.Ic unset .
To integrate other environment variables of choice into this
transparent handling, and also to export internal variables into the
process environment where they normally are not, a
.Ql link
needs to become established with this command, as in, e.g.,
.
.Pp
.Dl environ link PERL5LIB TZ
.
.Pp
Afterwards changing such variables with
.Ic set
will cause automatic updates of the program environment, and therefore
be inherited by newly created child processes.
Sufficient system support provided (it was in BSD as early as 1987, and
is standardized since Y2K) removing such variables with
.Ic unset
will remove them also from the program environment, but in any way
the knowledge they ever have been
.Ql link Ns
ed will be lost.
Note that this implies that
.Ic localopts
may cause loss of such links.
.
.Pp
The command
.Ql unlink
will remove an existing link, but leaves the variables as such intact.
Additionally the subcommands
.Ql set
and
.Ql unset
are provided, which work exactly the same as the documented commands
.Ic set
and
.Ic unset ,
but (additionally un)link the variable(s) with the program environment
and thus immediately export them to, or remove them from (if possible),
respectively, the program environment.
.
.
.Mx
.It Ic errors
\*(OP Since \*(UA uses the console as a user interface it can happen
that messages scroll by too fast to become recognized.
An error message ring queue is available which stores duplicates of any
error message and notifies the user in interactive sessions whenever
a new error has occurred.
The queue is finite: if its maximum size is reached any new message
replaces the eldest.
The command
.Ic errors
can be used to manage this message queue: if given
.Ar show
or no argument the queue will be displayed and cleared,
.Ar clear
will only clear all messages from the queue.
.
.Mx
.It Ic eval
\*(NQ Construct a command by concatenating the arguments, separated with
a single space character, and then evaluate the result.
This command passes through the exit status
.Va \&?
and error number
.Va \&!
of the evaluated command; also see
.Ic call .
.Bd -literal -offset indent
define xxx {
  echo "xxx arg <$1>"
  shift
  if [ $# -gt 0 ]
    \excall xxx "$@"
  endif
}
define yyy {
  eval "$@ ' ball"
}
call yyy '\ecall xxx' "b\e$'\et'u ' "
call xxx arg <b      u>
call xxx arg <  >
call xxx arg <ball>
.Ed
.
.Mx
.It Ic exit
(ex or x) Exit from \*(UA without changing the active mailbox and skip
any saving of messages in the
.Mx -sx
.Sx "secondary mailbox"
.Ev MBOX ,
as well as a possibly tracked line editor
.Va history-file .
The optional status number argument will be passed through to
.Xr exit 3 .
\*(ID For now it can happen that the given status will be overwritten,
later this will only occur if a later error needs to be reported onto an
otherwise success indicating status.
.
.Mx
.It Ic File
(Fi) Like
.Ic file ,
but open the mailbox read-only.
.
.
.Mx
.It Ic file
(fi) The file command switches to a new mailbox.
Without arguments it shows status information of the current mailbox.
If an argument is given, it will write out changes (such as deletions)
the user has made, open a new mailbox, update the internal variables
.Va mailbox-resolved
and
.Va mailbox-display ,
and optionally display a summary of
.Ic headers
if the variable
.Va header
is set.
.
.Pp
.Sx "Filename transformations"
will be applied to the
.Ar name
argument, and
.Ql protocol://
prefixes are, i.e., URL syntax is understood, e.g.,
.Ql maildir:///tmp/mdirbox :
if a protocol prefix is used the mailbox type is fixated and neither
the auto-detection (read on) nor the
.Va newfolders
mechanisms apply.
\*(OPally URLs can also be used to access network resources, and it is
possible to proxy all network traffic over a SOCKS5 server given via
.Va socks-proxy .
.
.Pp
.Dl \*(IN protocol://[user[:password]@]host[:port][/path]
.Dl \*(OU protocol://[user@]host[:port][/path]
.
.Pp
\*(OPally supported network protocols are
.Ar pop3
(POP3) and
.Ar pop3s
(POP3 with SSL/TLS encrypted transport),
.Ar imap
and
.Ar imaps .
The
.Ar [/path]
part is valid only for IMAP; there it defaults to
.Ar INBOX .
Network URLs require a special encoding as documented in the section
.Sx "On URL syntax and credential lookup" .
.
.Pp
If the resulting file protocol (MBOX database)
.Ar name
is located on a local filesystem then the list of all registered
.Ic filetype Ns
s is traversed in order to see whether a transparent intermediate
conversion step is necessary to handle the given mailbox, in which case
\*(UA will use the found hook to load and save data into and from
a temporary file, respectively.
Changing hooks will not affect already opened mailboxes.
For example, the following creates hooks for the
.Xr gzip 1
compression tool and a combined compressed and encrypted format:
.
.Bd -literal -offset indent
? filetype \e
    gzip 'gzip -dc' 'gzip -c' \e
    zst.pgp 'gpg -d | zstd -dc' 'zstd -19 -zc | gpg -e'
.Ed
.
.Pp
MBOX database files are generally locked during file operations in order
to avoid inconsistencies due to concurrent modifications.
\*(OPal Mailbox files which \*(UA treats as the system
.Va inbox
.Pf ( Ev MAIL ) ,
and
.Mx -sx
.Sx "primary system mailbox" Ns
es in general will also be protected by so-called dotlock files, the
traditional way of mail spool file locking: for any file
.Ql a
a lock file
.Ql a.lock
will be created for the duration of the synchronization \(em
as necessary a privilege-separated dotlock child process will be used
to accommodate for necessary privilege adjustments in order to create
the dotlock file in the same directory
and with the same user and group identities as the file of interest.
.
.Pp
\*(UA by default uses tolerant POSIX rules when reading MBOX database
files, but it will detect invalid message boundaries in this mode and
complain (even more with
.Va debug )
if any is seen: in this case
.Va mbox-rfc4155
can be used to create a valid MBOX database from the invalid input.
.
.Pp
If no protocol has been fixated, and
.Ar name
refers to a directory with the subdirectories
.Ql tmp ,
.Ql new
and
.Ql cur ,
then it is treated as a folder in
.Dq Maildir
format.
The maildir format stores each message in its own file, and has been
designed so that file locking is not necessary when reading or writing
files.
.
.Pp
\*(ID If no protocol has been fixated and no existing file has
been found, the variable
.Va newfolders
controls the format of mailboxes yet to be created.
.
.
.Mx
.Mx
.It Ic filetype , unfiletype
\*(NQ Define or list, and remove, respectively, file handler hooks,
which provide (shell) commands that enable \*(UA to load and save MBOX
files from and to files with the registered file extensions;
it will use an intermediate temporary file to store the plain data.
The latter command removes the hooks for all given extensions,
.Ql *
will remove all existing handlers.
.Pp
When used without arguments the former shows a list of all currently
defined file hooks, with one argument the expansion of the given alias.
Otherwise three arguments are expected, the first specifying the file
extension for which the hook is meant, and the second and third defining
the load- and save commands, respectively, to deal with the file type,
both of which must read from standard input and write to standard
output.
Changing hooks will not affect already opened mailboxes (\*(ID except below).
\*(ID For now too much work is done, and files are oftened read in twice
where once would be sufficient: this can cause problems if a filetype is
changed while such a file is opened; this was already so with the
built-in support of .gz etc. in Heirloom, and will vanish in v15.
\*(ID For now all handler strings are passed to the
.Ev SHELL for evaluation purposes; in the future a
.Ql \&!
prefix to load and save commands may mean to bypass this shell instance:
placing a leading space will avoid any possible misinterpretations.
.Bd -literal -offset indent
? filetype bz2 'bzip2 -dc' 'bzip2 -zc' \e
    gz 'gzip -dc' 'gzip -c'  xz 'xz -dc' 'xz -zc' \e
    zst 'zstd -dc' 'zstd -19 -zc' \e
    zst.pgp 'gpg -d | zstd -dc' 'zstd -19 -zc | gpg -e'
? set record=+sent.zst.pgp
.Ed
.
.Mx
.Mx
.It Ic flag , unflag
Take message lists and mark the messages as being flagged, or not being
flagged, respectively, for urgent/special attention.
See the section
.Sx "Message states" .
.
.Mx
.It Ic folder
(fold) The same as
.Ic file .
.
.Mx
.It Ic folders
With no arguments, list the names of the folders in the folder directory.
With an existing folder as an argument,
lists the names of folders below the named folder.
.
.Mx
.It Ic Followup
(F) Similar to
.Ic Respond ,
but saves the message in a file named after the local part of the first
recipient's address (instead of in
.Va record Ns ).
.
.Mx
.It Ic followup
(fo) Similar to
.Ic respond ,
but saves the message in a file named after the local part of the first
recipient's address (instead of in
.Va record Ns ).
.
.Mx
.It Ic followupall
Similar to
.Ic followup ,
but responds to all recipients regardless of the
.Va flipr
variable.
.
.Mx
.It Ic followupsender
Similar to
.Ic Followup ,
but responds to the sender only regardless of the
.Va flipr
variable.
.
.Mx
.It Ic Forward
Similar to
.Ic forward ,
but saves the message in a file named after the local part of the
recipient's address (instead of in
.Va record Ns ).
.
.Mx
.It Ic forward
Takes a message and the address of a recipient
and forwards the message to him.
The text of the original message is included in the new one,
with the value of the
.Va forward-inject-head
variable preceding it.
To filter the included header fields to the desired subset use the
.Ql forward
slot of the white- and blacklisting command
.Ic headerpick .
Only the first part of a multipart message is included unless
.Va forward-as-attachment ,
and recipient addresses will be stripped from comments, names etc.
unless the internal variable
.Va fullnames
is set.
.
.Mx
.It Ic from
(f) Takes a list of message specifications and displays a summary of
their message headers, exactly as via
.Ic headers .
An alias of this command is
.Ic search .
Also see
.Sx "Specifying messages" .
.
.It Ic Fwd
\*(OB Alias for
.Ic Forward .
.
.It Ic fwd
\*(OB Alias for
.Ic forward .
.
.It Ic fwdignore
\*(OB Superseded by the multiplexer
.Ic headerpick .
.
.It Ic fwdretain
\*(OB Superseded by the multiplexer
.Ic headerpick .
.
.It Ic ghost , unghost
\*(OB Replaced by
.Ic commandalias ,
.Ic uncommandalias .
.
.Mx
.Mx
.It Ic headerpick , unheaderpick
\*(NQ Multiplexer command to manage white- and blacklisting
selections of header fields for a variety of applications.
Without arguments the set of contexts that have settings is displayed.
When given arguments, the first argument is the context to which the
command applies, one of (case-insensitive)
.Ql type
for display purposes (via, e.g.,
.Ic type ) ,
.Ql save
for selecting which headers shall be stored persistently when
.Ic save ,
.Ic copy ,
.Ic move
or even
.Ic decrypt Ns
ing messages (note that MIME related etc. header fields should not be
ignored in order to not destroy usability of the message in this case),
.Ql forward
for stripping down messages when
.Ic forward Ns
ing message (has no effect if
.Va forward-as-attachment
is set), and
.Ql top
for defining user-defined set of fields for the command
.Ic top .
.Pp
The current settings of the given context are displayed if it is the
only argument.
A second argument denotes the type of restriction that is to be chosen,
it may be (a case-insensitive prefix of)
.Ql retain
or
.Ql ignore
for white- and blacklisting purposes, respectively.
Establishing a whitelist suppresses inspection of the corresponding
blacklist.
.Pp
If no further argument is given the current settings of the given type
will be displayed, otherwise the remaining arguments specify header
fields, which \*(OPally may be given as regular expressions, to be added
to the given type.
The special wildcard field (asterisk,
.Ql * )
will establish a (fast) shorthand setting which covers all fields.
.Pp
The latter command always takes three or more arguments and can be used
to remove selections, i.e., from the given context, the given type of
list, all the given headers will be removed, the special argument
.Ql *
will remove all headers.
.
.Mx
.It Ic headers
(h) Show the current group of headers, the size of which depends on
the variable
.Va screen ,
and the style of which can be adjusted with the variable
.Va headline .
If a message-specification is given the group of headers containing the
first message therein is shown and the message at the top of the screen
becomes the new
.Dq dot .
.
.Mx
.It Ic help
(hel) A synonym for
.Ic \&? .
.
.Mx
.It Ic history
\*(OP Either
.Ar show
(this mode also supports a more
.Va verbose
output) or
.Ar clear
the list of history entries;
a decimal
.Ar NUMBER
argument selects and evaluates the respective history entry,
which will become the new history top; a negative number is used as an
offset to the current command, e.g.,
.Ql -1
will select the last command, the history top.
The default mode if no arguments are given is
.Ar show .
Please see
.Sx "On terminal control and line editor"
for more on this topic.
.
.Mx
.It Ic hold
(ho, also
.Ic preserve )
Takes a message list and marks each message therein to be saved in the
user's system
.Va inbox
instead of in the
.Mx -sx
.Sx "secondary mailbox"
.Ev MBOX .
Does not override the
.Ic delete
command.
\*(UA deviates from the POSIX standard with this command, because a
.Ic next
command issued after
.Ic hold
will display the following message, not the current one.
.
.
.Mx
.It Ic if
(i) Part of the nestable
.Ic if Ns \0/\: Ic elif Ns \0/\: Ic else Ns \0/\: Ic endif
conditional execution construct \(em if the given condition is true then
the encapsulated block is executed.
The POSIX standards supports the (case-insensitive) conditions
.Ql r Ns
eceive
and
.Ql s Ns
end, all remaining conditions are non-portable extensions.
\*(ID These commands do not yet use
.Sx "Shell-style argument quoting"
and therefore do not know about input tokens, so that syntax
elements have to be surrounded by whitespace; in v15 \*(UA will inspect
all conditions bracket group wise and consider the tokens, representing
values and operators, therein, which also means that variables will
already have been expanded at that time (just like in the shell).
.
.Bd -literal -offset indent
if receive
  commands ...
else
  commands ...
endif
.Ed
.
.Pp
The (case-insensitive) condition
.Ql t Ns
erminal will evaluate to true if the standard input is a terminal, i.e.,
in interactive sessions.
Another condition can be any boolean value (see the section
.Sx "INTERNAL VARIABLES"
for textual boolean representations) to mark an enwrapped block as
.Dq never execute
or
.Dq always execute .
(It shall be remarked that a faulty condition skips all branches until
.Ic endif . )
.
.Pp
(\*(ID In v15
.Sx "Shell-style argument quoting"
will be used, and this command will simply interpret expanded tokens.)
It is possible to check
.Sx "INTERNAL VARIABLES"
as well as
.Sx ENVIRONMENT
variables for existence or compare their expansion against a user given
value or another variable by using the
.Ql $
.Pf ( Dq variable next )
conditional trigger character;
a variable on the right hand side may be signalled using the same
mechanism.
Variable names may be enclosed in a pair of matching braces.
When this mode has been triggered, several operators are available:
.
.Pp
Integer operators treat the arguments on the left and right hand side of
the operator as integral numbers and compare them arithmetically.
It is an error if any of the operands is not a valid integer, an empty
argument (which implies it had been quoted) is treated as if it were 0.
Available operators are
.Ql -lt
(less than),
.Ql -le
(less than or equal to),
.Ql -eq
(equal),
.Ql -ne
(not equal),
.Ql -ge
(greater than or equal to), and
.Ql -gt
(greater than).
.
.Pp
String data operators compare the left and right hand side according to
their textual content.
Unset variables are treated as the empty string.
The behaviour of string operators can be adjusted by prefixing the
operator with the modifier trigger commercial at
.Ql @ ,
followed by none to multiple modifiers: for now supported is
.Ql i ,
which turns the comparison into a case-insensitive one: this is
implied if no modifier follows the trigger.
.
.Pp
Available string operators are
.Ql <
(less than),
.Ql <=
(less than or equal to),
.Ql ==
(equal),
.Ql !=
(not equal),
.Ql >=
(greater than or equal to),
.Ql >
(greater than),
.Ql =%
(is substring of) and
.Ql !%
(is not substring of).
By default these operators work on bytes and (therefore) do not take
into account character set specifics.
If the case-insensitivity modifier has been used, case is ignored
according to the rules of the US-ASCII encoding, i.e., bytes are
still compared.
.
.Pp
When the \*(OPal regular expression support is available, the additional
string operators
.Ql =~
and
.Ql !~
can be used.
They treat the right hand side as an extended regular expression that is
matched according to the active locale (see
.Sx "Character sets" ) ,
i.e., character sets should be honoured correctly.
.
.Pp
Conditions can be joined via AND-OR lists (where the AND operator is
.Ql &&
and the OR operator is
.Ql || ) ,
which have equal precedence and will be evaluated with left
associativity, thus using the same syntax that is known for the
.Xr sh 1 .
It is also possible to form groups of conditions and lists by enclosing
them in pairs of brackets
.Ql [\ \&.\&.\&.\ ] ,
which may be interlocked within each other, and also be joined via
AND-OR lists.
.
.Pp
The results of individual conditions and entire groups may be modified
via unary operators: the unary operator
.Ql \&!
will reverse the result.
.
.Bd -literal -offset indent
# (This not in v15, there [ -n "$debug"]!)
if $debug
  echo *debug* is set
endif
if [ "$ttycharset" == UTF-8 ] || [ "$ttycharset" @i== UTF8 ]
  echo *ttycharset* is UTF-8, the former case-sensitive!
endif
set t1=one t2=one
if [ "${t1}" == "${t2}" ]
  echo These two variables are equal
endif
if [ "$features" =% +regex ] && [ "$TERM" @i=~ "^xterm\&.*" ]
  echo ..in an X terminal
endif
if [ [ true ] && [ [ "${debug}" != '' ] || \e
    [ "$verbose" != '' ] ] ]
  echo Noisy, noisy
endif
if true && [ "$debug" != '' ] || [ "${verbose}" != '' ]
  echo Left associativity, as is known from the shell
endif
.Ed
.
.
.Mx
.It Ic ignore
(ig) Identical to
.Ic discard .
Superseded by the multiplexer
.Ic headerpick .
.
.Mx
.It Ic list
Shows the names of all available commands, alphabetically sorted.
If given any non-whitespace argument the list will be shown in the order
in which command prefixes are searched.
\*(OP In conjunction with a set variable
.Va verbose
additional information will be provided for each command: the argument
type will be indicated, the documentation string will be shown,
and the set of command flags will show up:
.Pp
.Bl -tag -compact -width ".It Ql BaNg"
.It Ql "vput modifier"
command supports the command modifier
.Cm vput .
.It Ql "errno in *!*"
the error number is tracked in
.Va \&! .
.It Ql "needs box"
commands needs an active mailbox, a
.Ic file .
.It Ql "ok: batch or interactive"
command may only be used in interactive or
.Fl #
batch mode.
.It Ql "ok: send mode"
command can be used in send mode.
.It Ql "not ok: compose mode"
command is not available when in compose mode.
.It Ql "not ok: during startup"
command cannot be used during program startup, e.g., while loading
.Sx "Resource files" .
.It Ql "ok: in subprocess"
command is allowed to be used when running in a subprocess instance,
e.g., from within a macro that is called via
.Va on-compose-splice .
.El
.
.
.Mx
.It Ic localopts
This command can be used to localize changes to (linked)
.Sx ENVIRONMENT
as well as
.Sx "INTERNAL VARIABLES" ,
meaning that their state will be reverted to the former one once the
.Dq covered scope
is left.
It can only be used inside of macro definition blocks introduced by
.Ic account
or
.Ic define .
The covered scope of an
.Ic account
is left once a different account is activated, and some macros, notably
.Va folder-hook Ns s ,
use their own specific notion of covered scope, here it will be extended
until the folder is left again.
.
.Pp
This setting stacks up: i.e., if
.Ql macro1
enables change localization and calls
.Ql macro2 ,
which explicitly resets localization, then any value changes within
.Ql macro2
will still be reverted when the scope of
.Ql macro1
is left.
(Caveats: if in this example
.Ql macro2
changes to a different
.Ic account
which sets some variables that are already covered by localizations,
their scope will be extended, and in fact leaving the
.Ic account
will (thus) restore settings in (likely) global scope which actually
were defined in a local, macro private context!)
.
.Pp
This command takes one or two arguments, the optional first one
specifies an attribute that may be one of
.Cm scope ,
which refers to the current scope and is thus the default,
.Cm call ,
which causes any macro that is being
.Ic call Ns
ed to be started with localization enabled by default, as well as
.Cm call-fixate ,
which (if enabled) disallows any called macro to turn off localization:
like this it can be ensured that once the current scope regains control,
any changes made in deeper levels have been reverted.
The latter two are mutually exclusive.
The (second) argument is interpreted as a boolean (string, see
.Sx "INTERNAL VARIABLES" )
and states whether the given attribute shall be turned on or off.
.
.Bd -literal -offset indent
define temporary_settings {
  set possibly_global_option1
  localopts on
  set local_option1
  set local_option2
  localopts scope off
  set possibly_global_option2
}
.Ed
.
.
.Mx
.It Ic Lreply
Reply to messages that come in via known
.Pf ( Ic mlist )
or subscribed
.Pf ( Ic mlsubscribe )
mailing lists, or pretend to do so (see
.Sx "Mailing lists" ) :
on top of the usual
.Ic reply
functionality this will actively resort and even remove message
recipients in order to generate a message that is supposed to be sent to
a mailing list.
For example it will also implicitly generate a
.Ql Mail-Followup-To:
header if that seems useful, regardless of the setting of the variable
.Va followup-to .
For more documentation please refer to
.Sx "On sending mail, and non-interactive mode" .
.
.Mx
.It Ic Mail
Similar to
.Ic mail ,
but saves the message in a file named after the local part of the first
recipient's address (instead of in
.Va record Ns ).
.
.Mx
.It Ic mail
(m) Takes a (list of) recipient address(es) as (an) argument(s),
or asks on standard input if none were given;
then collects the remaining mail content and sends it out.
For more documentation please refer to
.Sx "On sending mail, and non-interactive mode" .
.
.Mx
.It Ic mbox
(mb) The given message list is to be sent to the
.Mx -sx
.Sx "secondary mailbox"
.Ev MBOX
when \*(UA is quit; this is the default action unless the variable
.Va hold
is set.
\*(ID This command can only be used in a
.Mx -sx
.Sx "primary system mailbox" .
.
.Mx
.Mx
.It Ic mimetype , unmimetype
Without arguments the content of the MIME type cache will displayed;
a more verbose listing will be produced if either of
.Va debug
or
.Va verbose
are set.
When given arguments they will be joined, interpreted as shown in
.Sx "The mime.types files"
(also see
.Sx "HTML mail and MIME attachments" ) ,
and the resulting entry will be added (prepended) to the cache.
In any event MIME type sources are loaded first as necessary \(en
.Va mimetypes-load-control
can be used to fine-tune which sources are actually loaded.
.Pp
The latter command deletes all specifications of the given MIME type, thus
.Ql ? unmimetype text/plain
will remove all registered specifications for the MIME type
.Ql text/plain .
The special name
.Ql *
will discard all existing MIME types, just as will
.Ql reset ,
but which also reenables cache initialization via
.Va mimetypes-load-control .
.
.Mx
.Mx
.It Ic mlist , unmlist
The latter command removes all given mailing-lists, the special name
.Ql *
can be used to remove all registered lists.
The former will list all currently defined mailing lists (and their
attributes, if any) when used without arguments; a more verbose listing
will be produced if either of
.Va debug
or
.Va verbose
are set.
Otherwise all given arguments will be added and henceforth be recognized
as mailing lists.
If the \*(OPal regular expression support is available then mailing
lists may also be specified as (extended) regular expressions (see
.Xr re_format 7
for more on those).
.
.Mx
.It Ic mimeview
\*(ID Only available in interactive mode, this command allows to display
MIME parts which require external MIME handler programs to run which do
not integrate in \*(UAs normal
.Ic type
output (see
.Sx "HTML mail and MIME attachments" ) .
(\*(ID No syntax to directly address parts, this restriction may vanish.)
The user will be asked for each non-text part of the given message in
turn whether the registered handler shall be used to display the part.
.
.Mx
.Mx
.It Ic mlsubscribe , unmlsubscribe
The latter command removes the subscription attribute from all given
mailing-lists, the special name
.Ql *
can be used to do so for any registered list.
The former will list all currently defined mailing lists which have
a subscription attribute when used without arguments; a more verbose
listing will be produced if either of
.Va debug
or
.Va verbose
are set.
Otherwise this attribute will be set for all given mailing lists,
newly creating them as necessary (as via
.Ic mlist ) .
Also see
.Va followup-to .
.
.Mx
.It Ic Move
Similar to
.Ic move ,
but moves the messages to a file named after the local part of the
sender address of the first message (instead of in
.Va record Ns ).
.
.Mx
.It Ic move
Acts like
.Ic copy
but marks the messages for deletion if they were transferred
successfully.
.
.Mx
.It Ic More
Like
.Ic more ,
but also displays header fields which would not pass the
.Ic headerpick
selection, and all MIME parts.
Identical to
.Ic Page .
.
.Mx
.It Ic more
Invokes the
.Ev PAGER
on the given messages, even in non-interactive mode and as long as the
standard output is a terminal.
Identical to
.Ic page .
.
.Mx
.It Ic netrc
\*(OP When used without arguments or if
.Ar show
has been given the content of the
.Pa .netrc
cache is shown, loading it first as necessary.
If the argument is
.Ar load
then the cache will only be initialized and
.Ar clear
will remove its contents.
Note that \*(UA will try to load the file only once, use
.Ql Ic \&\&netrc Ns \:\0\:clear
to unlock further attempts.
See
.Va netrc-lookup ,
.Va netrc-pipe
and the section
.Sx "On URL syntax and credential lookup" ;
the section
.Sx "The .netrc file"
documents the file format in detail.
.
.Mx
.It Ic newmail
Checks for new mail in the current folder without committing any changes
before.
If new mail is present, a message is shown.
If the
.Va header
variable is set,
the headers of each new message are also shown.
This command is not available for all mailbox types.
.
.Mx
.It Ic next
(n) (like
.Ql +
or
.Dq ENTER )
Goes to the next message in sequence and types it.
With an argument list, types the next matching message.
.
.Mx
.It Ic New
Same as
.Ic Unread .
.
.Mx
.It Ic new
Same as
.Ic unread .
.
.Mx
.It Ic noop
If the current folder is accessed via a network connection, a
.Dq NOOP
command is sent, otherwise no operation is performed.
.
.Mx
.It Ic Page
Like
.Ic page ,
but also displays header fields which would not pass the
.Ic headerpick
selection, and all MIME parts.
Identical to
.Ic More .
.
.Mx
.It Ic page
Invokes the
.Ev PAGER
on the given messages, even in non-interactive mode and as long as the
standard output is a terminal.
Identical to
.Ic more .
.
.Mx
.It Ic Pipe
Like
.Ic pipe
but also pipes header fields which would not pass the
.Ic headerpick
selection, and all parts of MIME
.Ql multipart/alternative
messages.
.
.Mx
.It Ic pipe
(pi) Takes a message list and a shell command
and pipes the messages through the command.
Without an argument the current message is piped through the command
given by the
.Va cmd
variable.
If the
.Va page
variable is set,
every message is followed by a formfeed character.
.
.Mx
.It Ic preserve
(pre) A synonym for
.Ic hold .
.
.Mx
.It Ic Print
(P) Alias for
.Ic Type .
.
.Mx
.It Ic print
(p) Research
.Ux
equivalent of
.Ic type .
.
.Mx
.It Ic quit
(q) Terminates the session, saving all undeleted, unsaved messages in
the current
.Mx -sx
.Sx "secondary mailbox"
.Ev MBOX ,
preserving all messages marked with
.Ic hold
or
.Ic preserve
or never referenced in the system
.Va inbox ,
and removing all other messages from the
.Mx -sx
.Sx "primary system mailbox" .
If new mail has arrived during the session,
the message
.Dq You have new mail
will be shown.
If given while editing a mailbox file with the command line option
.Fl f ,
then the edit file is rewritten.
A return to the shell is effected,
unless the rewrite of edit file fails,
in which case the user can escape with the exit command.
The optional status number argument will be passed through to
.Xr exit 3 .
\*(ID For now it can happen that the given status will be overwritten,
later this will only occur if a later error needs to be reported onto an
otherwise success indicating status.
.
.Mx
.It Ic read
\*(NQ Read a line from standard input, or the channel set active via
.Ic readctl ,
and assign the data, which will be splitted as indicated by
.Va ifs ,
to the given variables.
The variable names are checked by the same rules as documented for
.Cm vput ,
and the same error codes will be seen in
.Va \&! ;
the exit status
.Va \&?
indicates the number of bytes read, it will be
.Ql -1
with the error number
.Va \&!
set to
.Va ^ERR Ns -BADF
in case of I/O errors, or
.Va ^ERR Ns -NONE
upon End-Of-File.
If there are more fields than variables, assigns successive fields to the
last given variable.
If there are less fields than variables, assigns the empty string to the
remains.
.Bd -literal -offset indent
? read a b c
   H  e  l  l  o
? echo "<$a> <$b> <$c>"
<H> <e> <l  l  o>
? wysh set ifs=:; read a b c;unset ifs
hey2.0,:"'you    ",:world!:mars.:
? echo $?/$^ERRNAME / <$a><$b><$c>
0/NONE / <hey2.0,><"'you    ",><world!:mars.:><><>
.Ed
.
.Mx
.It Ic readctl
\*(NQ Manages input channels for
.Ic read ,
to be used to avoid complicated or impracticable code, like calling
.Ic \&\&read
from within a macro in non-interactive mode.
Without arguments, or when the first argument is
.Cm show ,
a listing of all known channels is printed.
Channels can otherwise be
.Cm create Ns
d, and existing channels can be
.Cm set
active and
.Cm remove Ns
d by giving the string used for creation.
.Pp
The channel name is expected to be a file descriptor number, or,
if parsing the numeric fails, an input file name that undergoes
.Sx "Filename transformations" .
E.g. (this example requires a modern shell):
.Bd -literal -offset indent
$ LC_ALL=C printf 'echon "hey, "\enread a\enyou\enecho $a' |\e
  LC_ALL=C \*(uA -R#
hey, you
$ LC_ALL=C printf 'echon "hey, "\enread a\enecho $a' |\e
  LC_ALL=C 6<<< 'you' \*(uA -R#X'readctl create 6'
hey, you
.Ed
.
.It Ic redirect
\*(OB Same as
.Ic resend .
.
.It Ic Redirect
\*(OB Same as
.Ic Resend .
.
.Mx
.It Ic remove
Removes the named files or directories.
If a name refer to a mailbox, e.g., a Maildir mailbox, then a mailbox
type specific removal will be performed, deleting the complete mailbox.
The user is asked for confirmation in interactive mode.
.
.Mx
.It Ic rename
Takes the name of an existing folder
and the name for the new folder
and renames the first to the second one.
Both folders must be of the same type.
.
.Mx
.It Ic Reply
(R) Replies to only the sender of each message of the given message
list, by using the first message as the template to quote, for the
.Ql Subject:
etc.
.Va flipr
will exchange this command with
.Ic reply .
Unless the internal variable
.Va fullnames
is set the recipient address will be stripped from comments, names etc.
.
.Mx
.It Ic reply
(r) Take a message and group-responds to it by addressing the sender
and all recipients, subject to
.Ic alternates
processing.
.Va followup-to ,
.Va followup-to-honour ,
.Va reply-to-honour
as well as
.Va recipients-in-cc
influence response behaviour.
Unless the internal variable
.Va fullnames
is set recipient addresses will be stripped from comments, names etc.
If
.Va flipr
is set the commands
.Ic Reply
and
.Ic reply
are exchanged.
The command
.Ic Lreply
offers special support for replying to mailing lists.
For more documentation please refer to
.Sx "On sending mail, and non-interactive mode" .
.
.Mx
.It Ic replyall
Similar to
.Ic reply ,
but initiates a group-reply regardless of the value of
.Va flipr .
.
.Mx
.It Ic replysender
Similar to
.Ic Reply ,
but responds to the sender only regardless of the value of
.Va flipr .
.
.Mx
.It Ic Resend
Like
.Ic resend ,
but does not add any header lines.
This is not a way to hide the sender's identity,
but useful for sending a message again to the same recipients.
.
.Mx
.It Ic resend
Takes a list of messages and a user name
and sends each message to the named user.
.Ql Resent-From:
and related header fields are prepended to the new copy of the message.
Saving in
.Va record
is only performed if
.Va record-resent
is set.
.
.Mx
.It Ic Respond
Same as
.Ic Reply .
.
.Mx
.It Ic respond
Same as
.Ic reply .
.
.Mx
.It Ic respondall
Same as
.Ic replyall .
.
.Mx
.It Ic respondsender
Same as
.Ic replysender .
.
.Mx
.It Ic retain
(ret) Superseded by the multiplexer
.Ic headerpick .
.
.Mx
.It Ic return
Only available inside the scope of a
.Ic define Ns
d macro or an
.Ic account ,
this will stop evaluation of any further macro content, and return
execution control to the caller.
The two optional parameters must be specified as positive decimal
numbers and default to the value 0:
the first argument specifies the signed 32-bit return value (stored in
.Va \&?
\*(ID and later extended to signed 64-bit),
the second the signed 32-bit error number (stored in
.Va \&! ) .
As documented for
.Va \&?
a non-0 exit status may cause the program to exit.
.
.Mx
.It Ic Save
(S) Similar to
.Ic save,
but saves the messages in a file named after the local part of the
sender of the first message instead of (in
.Va record
and) taking a filename argument; the variable
.Va outfolder
is inspected to decide on the actual storage location.
.
.Mx
.It Ic save
(s) Takes a message list and a filename and appends each message in turn
to the end of the file.
If no filename is given, the
.Mx -sx
.Sx "secondary mailbox"
.Ev MBOX
is used.
The filename in quotes, followed by the generated character count
is echoed on the user's terminal.
If editing a
.Mx -sx
.Sx "primary system mailbox"
the messages are marked for deletion.
.Sx "Filename transformations"
will be applied.
.
.It Ic savediscard
\*(OB Superseded by the multiplexer
.Ic headerpick .
.
.It Ic saveignore
\*(OB Superseded by the multiplexer
.Ic headerpick .
.
.It Ic saveretain
\*(OB Superseded by the multiplexer
.Ic headerpick .
.
.Mx
.It Ic search
Takes a message specification (list) and displays a header summary of
all matching messages, as via
.Ic headers .
This command is an alias of
.Ic from .
Also see
.Sx "Specifying messages" .
.
.Mx
.It Ic seen
Takes a message list and marks all messages as having been read.
.
.
.Mx
.Mx
.It Ic set , unset
(se, \*(NQ uns) The latter command will delete all given variables,
the former, when used without arguments, will show all variables which
are currently known to \*(UA.
A more verbose listing will be produced if
either of
.Va debug
or
.Va verbose
are set.
Remarks: the list mode will not automatically link-in known
.Sx ENVIRONMENT
variables, but only explicit addressing will, e.g., via
.Ic varshow ,
using a variable in an
.Ic if
condition or a string passed to
.Ic echo ,
explicit
.Ic set Ns
ting, as well as some program-internal use cases.
.
.Pp
Otherwise the given variables (and arguments) are set or adjusted.
Arguments are of the form
.Ql name=value
(no space before or after
.Ql = ) ,
or plain
.Ql name
if there is no value, i.e., a boolean variable.
\*(ID In conjunction with the
.Cm wysh
command prefix
.Sx "Shell-style argument quoting"
can be used to quote arguments as necessary.
\*(ID Otherwise quotation marks may be placed around any part of the
assignment statement to quote blanks or tabs.
.
.Pp
.Dl ? wysh set indentprefix=' -> '
.
.Pp
If an argument begins with
.Ql no ,
as in
.Ql set nosave ,
the effect is the same as invoking the
.Ic unset
command with the remaining part of the variable
.Pf ( Ql unset save ) .
.
.Pp
Any
.Ql name
that is known to map to an environment variable will automatically cause
updates in the program environment (unsetting a variable in the
environment requires corresponding system support) \(em use the command
.Ic environ
for further environmental control.
Also see
.Ic varedit ,
.Ic varshow
and the sections
.Sx "INTERNAL VARIABLES"
and
.Sx ENVIRONMENT .
.
.
.Mx
.It Ic shcodec
Apply shell quoting rules to the given raw-data arguments.
Supports
.Cm vput
(see
.Sx "Command modifiers" ) .
The first argument specifies the operation:
.Ar [+]e[ncode]
or
.Ar d[ecode]
cause shell quoting to be applied to the remains of the line, and
expanded away thereof, respectively.
If the former is prefixed with a plus-sign, the quoted result will not
be roundtrip enabled, and thus can be decoded only in the very same
environment that was used to perform the encode; also see
.Cd mle-quote-rndtrip .
If the coding operation fails the error number
.Va \&!
is set to
.Va ^ERR Ns -CANCELED ,
and the unmodified input is used as the result; the error number may
change again due to output or result storage errors.
.
.Mx
.It Ic shell
\*(NQ (sh) Invokes an interactive version of the shell,
and returns its exit status.
.
.Mx
.Mx
.It Ic shortcut , unshortcut
Without arguments the list of all currently defined shortcuts is
shown, with one argument the expansion of the given shortcut.
Otherwise all given arguments are treated as pairs of shortcuts and
their expansions, creating new or changing already existing shortcuts,
as necessary.
The latter command will remove all given shortcuts, the special name
.Ql *
will remove all registered shortcuts.
.
.Mx
.It Ic shift
\*(NQ Shift the positional parameter stack (starting at
.Va 1 )
by the given number (which must be a positive decimal),
or 1 if no argument has been given.
It is an error if the value exceeds the number of positional parameters.
If the given number is 0, no action is performed, successfully.
The stack as such can be managed via
.Ic vpospar .
Note this command will fail in
.Ic account
and hook macros unless the positional parameter stack has been
explicitly created in the current context via
.Ic vpospar .
.
.Mx
.It Ic show
Like
.Ic type ,
but performs neither MIME decoding nor decryption, so that the raw
message text is shown.
.
.Mx
.It Ic size
(si) Shows the size in characters of each message of the given
message-list.
.
.Mx
.It Ic sleep
\*(NQ Sleep for the specified number of seconds (and optionally
milliseconds), by default interruptably.
If a third argument is given the sleep will be uninterruptible,
otherwise the error number
.Va \&!
will be set to
.Va ^ERR Ns -INTR
if the sleep has been interrupted.
The command will fail and the error number will be
.Va ^ERR Ns -OVERFLOW
if the given duration(s) overflow the time datatype, and
.Va ^ERR Ns -INVAL
if the given durations are no valid integers.
.
.
.Mx
.Mx
.It Ic sort , unsort
The latter command disables sorted or threaded mode, returns to normal
message order and, if the
.Va header
variable is set,
displays a header summary.
The former command shows the current sorting criterion when used without
an argument, but creates a sorted representation of the current folder
otherwise, and changes the
.Ic next
command and the addressing modes such that they refer to messages in
the sorted order.
Message numbers are the same as in regular mode.
If the
.Va header
variable is set,
a header summary in the new order is also displayed.
Automatic folder sorting can be enabled by setting the
.Va autosort
variable, as in, e.g.,
.Ql set autosort=thread .
Possible sorting criterions are:
.
.Pp
.Bl -tag -compact -width "subject"
.It Ar date
Sort the messages by their
.Ql Date:
field, that is by the time they were sent.
.It Ar from
Sort messages by the value of their
.Ql From:
field, that is by the address of the sender.
If the
.Va showname
variable is set, the sender's real name (if any) is used.
.It Ar size
Sort the messages by their size.
.It spam
\*(OP Sort the message by their spam score, as has been classified by
.Ic spamrate .
.It Ar status
Sort the messages by their message status.
.It Ar subject
Sort the messages by their subject.
.It Ar thread
Create a threaded display.
.It Ar to
Sort messages by the value of their
.Ql To:
field, that is by the address of the recipient.
If the
.Va showname
variable is set, the recipient's real name (if any) is used.
.El
.
.
.Mx
.It Ic source
\*(NQ (so) The source command reads commands from the given file.
.Sx "Filename transformations"
will be applied.
If the given expanded argument ends with a vertical bar
.Ql |
then the argument will instead be interpreted as a shell command and
\*(UA will read the output generated by it.
Interpretation of commands read is stopped when an error is encountered.
\*(ID Note that
.Ic \&\&source
cannot be used from within macros that execute as
.Va folder-hook Ns s
or
.Ic account Ns s ,
i.e., it can only be called from macros that were
.Ic call Ns ed .
.
.Mx
.It Ic source_if
\*(NQ The difference to
.Ic source
(beside not supporting pipe syntax aka shell command input) is that
this command will not generate an error nor warn if the given file
argument cannot be opened successfully.
.
.Mx
.It Ic spamclear
\*(OP Takes a list of messages and clears their
.Ql is-spam
flag.
.
.Mx
.It Ic spamforget
\*(OP Takes a list of messages and causes the
.Va spam-interface
to forget it has ever used them to train its Bayesian filter.
Unless otherwise noted the
.Ql is-spam
flag of the message is inspected to chose whether a message shall be
forgotten to be
.Dq ham
or
.Dq spam .
.
.Mx
.It Ic spamham
\*(OP Takes a list of messages and informs the Bayesian filter of the
.Va spam-interface
that they are
.Dq ham .
This also clears the
.Ql is-spam
flag of the messages in question.
.
.Mx
.It Ic spamrate
\*(OP Takes a list of messages and rates them using the configured
.Va spam-interface ,
without modifying the messages, but setting their
.Ql is-spam
flag as appropriate; because the spam rating headers are lost the rate
will be forgotten once the mailbox is left.
Refer to the manual section
.Sx "Handling spam"
for the complete picture of spam handling in \*(UA.
.
.Mx
.It Ic spamset
\*(OP Takes a list of messages and sets their
.Ql is-spam
flag.
.
.Mx
.It Ic spamspam
\*(OP Takes a list of messages and informs the Bayesian filter of the
.Va spam-interface
that they are
.Dq spam .
This also sets the
.Ql is-spam
flag of the messages in question.
.
.It Ic thread
\*(OB The same as
.Ql sort thread
(consider using a
.Ql commandalias
as necessary).
.
.Mx
.It Ic Top
Like
.Ic top
but always uses the
.Ic headerpick
.Ql type
slot for white- and blacklisting header fields.
.
.Mx
.It Ic top
(to) Takes a message list and types out the first
.Va toplines
lines of each message on the users' terminal.
Unless a special selection has been established for the
.Ql top
slot of the
.Ic headerpick
command, the only header fields that are displayed are
.Ql From: ,
.Ql To: ,
.Ql CC: ,
and
.Ql Subject: .
.Ic Top
will always use the
.Ql type
.Ic headerpick
selection instead.
It is possible to apply compression to what is displayed by setting
.Va topsqueeze .
Messages are decrypted and converted to the terminal character set
if necessary.
.
.Mx
.It Ic touch
(tou) Takes a message list and marks the messages for saving in the
.Mx -sx
.Sx "secondary mailbox"
.Ev MBOX .
\*(UA deviates from the POSIX standard with this command,
as a following
.Ic next
command will display the following message instead of the current one.
.
.Mx
.It Ic Type
(T) Like
.Ic type
but also displays header fields which would not pass the
.Ic headerpick
selection, and all visualizable parts of MIME
.Ql multipart/alternative
messages.
.
.Mx
.It Ic type
(t) Takes a message list and types out each message on the users terminal.
The display of message headers is selectable via
.Ic headerpick .
For MIME multipart messages, all parts with a content type of
.Ql text ,
all parts which have a registered MIME type handler (see
.Sx "HTML mail and MIME attachments" )
which produces plain text output, and all
.Ql message
parts are shown, others are hidden except for their headers.
Messages are decrypted and converted to the terminal character set
if necessary.
The command
.Ic mimeview
can be used to display parts which are not displayable as plain text.
.
.It Ic unaccount
See
.Ic account .
.
.It Ic unalias
(una) See
.Ic alias .
.
.It Ic unanswered
See
.Ic answered .
.
.It Ic unbind
See
.Ic bind .
.
.It Ic uncollapse
See
.Ic collapse .
.
.It Ic uncolour
See
.Ic colour .
.
.It Ic undefine
See
.Ic define .
.
.It Ic undelete
See
.Ic delete .
.
.It Ic undraft
See
.Ic draft .
.
.It Ic unflag
See
.Ic flag .
.
.It Ic unfwdignore
\*(OB Superseded by the multiplexer
.Ic headerpick .
.
.It Ic unfwdretain
\*(OB Superseded by the multiplexer
.Ic headerpick .
.
.Mx
.It Ic unignore
Superseded by the multiplexer
.Ic headerpick .
.
.It Ic unmimetype
See
.Ic mimetype .
.
.It Ic unmlist
See
.Ic mlist .
.
.It Ic unmlsubscribe
See
.Ic mlsubscribe .
.
.Mx
.It Ic Unread
Same as
.Ic unread .
.
.Mx
.It Ic unread
Takes a message list and marks each message as not having been read.
.
.Mx
.It Ic unretain
Superseded by the multiplexer
.Ic headerpick .
.
.It Ic unsaveignore
\*(OB Superseded by the multiplexer
.Ic headerpick .
.
.It Ic unsaveretain
\*(OB Superseded by the multiplexer
.Ic headerpick .
.
.It Ic unset
\*(NQ (uns) See
.Ic set .
.
.It Ic unshortcut
See
.Ic shortcut .
.
.It Ic unsort
See
.Ic short .
.
.It Ic unthread
\*(OB
Same as
.Ic unsort .
.
.Mx
.It Ic urlcodec
Perform URL percent codec operations on the raw-data argument, rather
according to RFC 3986.
Supports
.Cm vput
(see
.Sx "Command modifiers" ) ,
and manages the error number
.Va \&! .
This is a character set agnostic and thus locale dependent operation,
and it may decode bytes which are invalid in the current
.Va ttycharset .
\*(ID This command does not know about URLs beside that.
.Pp
The first argument specifies the operation:
.Ar e[ncode]
or
.Ar d[ecode]
perform plain URL percent en- and decoding, respectively.
.Ar p[ath]enc[ode]
and
.Ar p[ath]dec[ode]
perform a slightly modified operation which should be better for
pathnames: it does not allow a tilde
.Ql ~ ,
and will neither accept hyphen-minus
.Ql -
nor dot
.Ql .
as an initial character.
The remains of the line form the URL data which is to be converted.
If the coding operation fails the error number
.Va \&!
is set to
.Va ^ERR Ns -CANCELED ,
and the unmodified input is used as the result; the error number may
change again due to output or result storage errors.
.
.Mx
.It Ic varedit
\*(NQ Edit the values of or create the given variable(s) in the
.Ev EDITOR .
Boolean variables cannot be edited, and variables can also not be
.Ic unset
with this command.
.
.Mx
.It Ic varshow
\*(NQ This command produces the same output as the listing mode of
.Ic set ,
including
.Va verbose Ns
ity adjustments, but only for the given variables.
.
.Mx
.It Ic verify
\*(OP Takes a message list and verifies each message.
If a message is not a S/MIME signed message,
verification will fail for it.
The verification process checks if the message was signed using a valid
certificate,
if the message sender's email address matches one of those contained
within the certificate,
and if the message content has been altered.
.
.Mx
.It Ic version
Shows the
.Va version
and
.Va features
of \*(UA.
.
.
.Mx
.It Ic vexpr
\*(NQ Evaluate arguments according to a given operator.
This is a multiplexer command which can be used to perform signed 64-bit
numeric calculations as well as byte string and string operations.
It uses polish notation, i.e., the operator is the first argument and
defines the number and type, and the meaning of the remaining arguments.
An empty argument is replaced with a 0 if a number is expected.
Supports
.Cm vput
(see
.Sx "Command modifiers" ) .
.
.Pp
The result that is shown in case of errors is always
.Ql -1
for usage errors and numeric operations, and the empty string for byte
string and string operations;
if the latter two fail to provide result data for
.Dq soft
errors, e.g., when a search operation failed, they also set the
.Va \&!
error number to
.Va ^ERR Ns -NODATA .
Except when otherwise noted numeric arguments are parsed as signed 64-bit
numbers, and errors will be reported in the error number
.Va \&!
as the numeric error
.Va ^ERR Ns -RANGE .
.
.Pp
Numeric operations work on one or two signed 64-bit integers.
One integer is expected by assignment (equals sign
.Ql = ) ,
which does nothing but parsing the argument, thus detecting validity and
possible overflow conditions, and unary not (tilde
.Ql ~ ) ,
which creates the bitwise complement.
Two integers are used by addition (plus sign
.Ql + ) ,
subtraction (hyphen-minus
.Ql - ) ,
multiplication (asterisk
.Ql * ) ,
division (solidus
.Ql / )
and modulo (percent sign
.Ql % ) ,
as well as for the bitwise operators logical or (vertical bar
.Ql | ,
to be quoted) ,
bitwise and (ampersand
.Ql \&& ,
to be quoted) ,
bitwise xor (circumflex
.Ql ^ ) ,
the bitwise signed left- and right shifts
.Pf ( Ql << ,
.Ql >> ) ,
as well as for the unsigned right shift
.Ql >>> .
.
.Pp
All numeric operators can be suffixed with a commercial at
.Ql @ ,
e.g.,
.Ql *@ :
this will turn the operation into a saturated one, which means that
overflow errors and division and modulo by zero are no longer reported
via the exit status, but the result will linger at the minimum or
maximum possible value, instead of overflowing (or trapping).
This is true also for the argument parse step.
For the bitwise shifts, the saturated maximum is 63.
Any catched overflow will be reported via the error number
.Va \&!
as
.Va ^ERR Ns -OVERFLOW .
.
.Pp
Character set agnostic string functions have no notion of locale
settings and character sets.
There is
.Ql file-expand ,
which performs the usual
.Sx "Filename transformations"
on its argument, and
.Ql random ,
which generates a random string of the given length, or of
.Dv \&\&PATH_MAX
bytes (a constant from
.Pa /usr/include )
if the value 0 is given; the random string will be base64url encoded
according to RFC 4648, and thus be usable as a (portable) filename.
.
.Pp
Byte string operations work on 8-bit bytes and have no notion of locale
settings and character sets, effectively assuming ASCII data.
Operations that take one argument are
.Ql length ,
which queries the length of the given argument, and
.Ql hash ,
which calculates the Chris Torek hash of the given argument.
.
.Pp
Byte string operations with two or more arguments are
.Ql find ,
which byte-searches in the first for the second argument, and shows the
resulting 0-based offset shall it have been found,
.Ql ifind ,
which is identical to
.Ql find ,
but works case-insensitively according to the rules of the ASCII
character set.
.Ql substring
will show a substring of its first argument:
the second argument is the 0-based starting offset, the optional third
argument can be used to specify the length of the desired substring,
by default the entire string is used;
this operation tries to work around faulty arguments (set
.Va verbose
for error logs), but reports them via the error number
.Va \&!
as
.Va ^ERR Ns -OVERFLOW .
.
.Pp
String operations work, sufficient support provided, according to the
active user's locale encoding and character set (see
.Sx "Character sets" ) .
There is the one argument operation
.Ql makeprint ,
which (one-way) converts the argument to something safely printable on
the terminal.
.
.Pp
\*(OP
.Ql regex
is a string operation that will try to match the first argument with the
regular expression given as the second argument, as does
.Ql iregex ,
but which is case-insensitive.
If the optional third argument has been given then instead of showing
the match offset a replacement operation is performed:
the third argument is treated as if specified via dollar-single-quote
(see
.Sx "Shell-style argument quoting" ) ,
and any occurrence of a positional parameter, e.g.,
.Va 1 ,
is replaced by the corresponding match group of the regular expression.
.
.Bd -literal -offset indent
? vexpr -@ +1 -9223372036854775808
? vput vexpr res ir bananarama (.*)NanA(.*) '\e${1}au\e$2'
? echo $0 $res
.Ed
.
.
.Mx
.It Ic vpospar
\*(NQ Manage the positional parameter stack (see
.Va 1 , # , * , @
as well as
.Ic shift ) .
If the first argument is
.Ql clear ,
then the positional parameter stack of the current context, or the
global one, if there is none, is cleared.
If it is
.Ql set ,
then the remaining arguments will be used to (re)create the stack,
if the parameter stack size limit is excessed an
.Va ^ERR Ns -OVERFLOW
error will occur.
.
.Pp
If the first argument is
.Ql quote ,
a round-trip capable representation of the stack contents is created,
with each quoted parameter separated from each other with the first
character of
.Va ifs ,
and followed by the first character of
.Va if-ws ,
if that is not empty and not identical to the first.
If that results in no separation at all a
.Cm space
character is used.
This mode supports
.Cm vput
(see
.Sx "Command modifiers" ) .
I.e., the subcommands
.Ql set
and
.Ql quote
can be used (in conjunction with
.Ic eval )
to (re)create an argument stack from and to a single variable losslessly.
.
.Bd -literal -offset indent
? vpospar set hey, "'you    ", world!
? echo $#: <${1}><${2}><${3}>
? vput vpospar x quote
? vpospar clear
? echo $#: <${1}><${2}><${3}>
? eval vpospar set ${x}
? echo $#: <${1}><${2}><${3}>
.Ed
.
.
.Mx
.It Ic visual
(v) Takes a message list and invokes the display editor on each message.
Modified contents are discarded unless the
.Va writebackedited
variable is set, and are not used unless the mailbox can be written to
and the editor returns a successful exit status.
.
.Mx
.It Ic write
(w) For conventional messages the body without all headers is written.
The original message is never marked for deletion in the originating
mail folder.
The output is decrypted and converted to its native format as necessary.
If the output file exists, the text is appended.
If a message is in MIME multipart format its first part is written to
the specified file as for conventional messages, handling of the remains
depends on the execution mode.
No special handling of compressed files is performed.
.Pp
In interactive mode the user is consecutively asked for the filenames of
the processed parts.
For convience saving of each part may be skipped by giving an empty
value, the same result as writing it to
.Pa /dev/null .
Shell piping the part content by specifying a leading vertical bar
.Ql |
character for the filename is supported.
Other user input undergoes the usual
.Sx "Filename transformations" ,
and contents of the destination file are overwritten if the file
previously existed.
.Pp
\*(ID In non-interactive mode any part which does not specify a filename
is ignored, and suspicious parts of filenames of the remaining parts are
URL percent encoded (as via
.Ic urlcodec )
to prevent injection of malicious character sequences, resulting in
a filename that will be written into the current directory.
Existing files will not be overwritten, instead the part number or
a dot are appended after a number sign
.Ql #
to the name until file creation succeeds (or fails due to other
reasons).
.
.Mx
.It Ic xcall
\*(NQ The sole difference to
.Ic call
is that the new macro is executed in place of the current one, which
will not regain control: all resources of the current macro will be
released first.
This implies that
.Ic localopts
may become cleaned up if the teared down macro context is the outermost
level of the cleanup stack.
If this command is not used from within a
.Ic call Ns
ed macro it will silently be (a more expensive variant of)
.Ic call .
.
.Mx
.It Ic xit
(x) A synonym for
.Ic exit .
.
.Mx
.It Ic z
\*(NQ \*(UA presents message headers in
.Va screen Ns
fuls as described under the
.Ic headers
command.
Without arguments this command scrolls to the next window of messages,
likewise if the argument is
.Ql + .
An argument of
.Ql -
scrolls to the last,
.Ql ^
scrolls to the first, and
.Ql $
to the last
.Va \&\&screen
of messages.
A number argument prefixed by
.Ql +
or
.Ql \-
indicates that the window is calculated in relation to the current
position, and a number without a prefix specifies an absolute position.
.
.Mx
.It Ic Z
\*(NQ Similar to
.Ic z ,
but scrolls to the next or previous window that contains at least one
.Ql new
or
.Ic flag Ns
ged message.
.El
.\" }}}
.
.\" }}}
.
.
.\" .Sh COMMAND ESCAPES {{{
.Sh "COMMAND ESCAPES"
.
Here is a summary of the command escapes available in compose mode,
which are used to perform special functions when composing messages.
Command escapes are only recognized at the beginning of lines, and
consist of a trigger (escape) and a command character.
The actual escape character can be set via the internal variable
.Va escape ,
it defaults to the tilde
.Ql ~ .
Otherwise ignored whitespace characters following the escape character
will prevent a possible addition of the command line to the \*(OPal
history.
.
.Pp
Unless otherwise noted all compose mode command escapes ensure proper
updates of the variables which represent the error number
.Va \&!
and the exit status
.Va \&? .
If the variable
.Va errexit
is set they will, unless stated otherwise, error out message compose
mode if an operation fails.
It is however possible to place the character hyphen-minus
.Ql -
after (possible whitespace following) the escape character, which has an
effect equivalent to the command modifier
.Cm ignerr .
If the \*(OPal key bindings are available it is possible to create
.Ic bind Ns
ings specifically for the compose mode.
.
.
.Bl -tag -width ".It Ic BaNg"
.Mx
.It Ic ~~ Ar string
Insert the string of text in the message prefaced by a single
.Ql ~ .
(If the escape character has been changed,
that character must be doubled instead.)
.
.Mx
.It Ic ~! Ar command
Execute the indicated shell
.Ar command
which follows, replacing unescaped exclamation marks with the previously
executed command if the internal variable
.Va bang
is set, then return to the message.
.
.Mx
.It Ic ~.
Same effect as typing the end-of-file character.
.
.Mx
.It Ic ~: Ar \*(UA-command Ns \0or Ic ~_ Ar \*(UA-command
Execute the given \*(UA command.
Not all commands, however, are allowed.
.
.Mx
.It Ic ~?
Write a summary of command escapes.
.
.Mx
.It Ic ~< Ar filename
Identical to
.Ic ~r .
.
.Mx
.It Ic ~<! Ar command
.Ar command
is executed using the shell.
Its standard output is inserted into the message.
.
.Mx
.It Ic ~@ Op Ar filename...
Append or edit the list of attachments.
Does not manage the error number
.Va \&!
and the exit status
.Va \&? ,
(please use
.Ic ~^
instead if this is a concern).
A list of
.Ar filename
arguments is expected as shell tokens (see
.Sx "Shell-style argument quoting" ;
token-separating commas are ignored, too), to be
interpreted as documented for the command line option
.Fl a ,
with the message number exception as below.
.Pp
Without
.Ar filename
arguments the attachment list is edited, entry by entry;
if a filename is left empty, that attachment is deleted from the list;
once the end of the list is reached either new attachments may be
entered or the session can be quit by committing an empty
.Dq new
attachment.
.Pp
For all mode, if a given filename solely consists of the number sign
.Ql #
followed by a valid message number of the currently active mailbox, then
the given message is attached as a
.Ql message/rfc822
MIME message part.
As the shell comment character the number sign must be quoted.
.
.Mx
.It Ic ~A
Inserts the string contained in the
.Va Sign
variable (same as
.Ql Ic ~i Ns \0Sign ) .
\*(OB The escape sequences tabulator
.Ql \et
and newline
.Ql \en
are understood (use the
.Cm wysh
prefix when
.Ic set Ns
ting the variable(s) instead).
.
.Mx
.It Ic ~a
Inserts the string contained in the
.Va sign
variable (same as
.Ql Ic ~i Ns \0sign ) .
\*(OB The escape sequences tabulator
.Ql \et
and newline
.Ql \en
are understood (use the
.Cm wysh
prefix when
.Ic set Ns
ting the variable(s) instead).
.
.Mx
.It Ic ~b Ar name ...
Add the given names to the list of blind carbon copy recipients.
.
.Mx
.It Ic ~c Ar name ...
Add the given names to the list of carbon copy recipients.
.
.Mx
.It Ic ~d
Read the file specified by the
.Ev DEAD
variable into the message.
.
.Mx
.It Ic ~e
Invoke the text editor on the message collected so far.
After the editing session is finished,
the user may continue appending text to the message.
.
.Mx
.It Ic ~F Ar messages
Read the named messages into the message being sent, including all
message headers and MIME parts.
If no messages are specified, read in the current message, the
.Dq dot .
.
.Mx
.It Ic ~f Ar messages
Read the named messages into the message being sent.
If no messages are specified, read in the current message, the
.Dq dot .
Strips down the list of header fields according to the
.Ql type
white- and blacklist selection of
.Ic headerpick .
For MIME multipart messages,
only the first displayable part is included.
.
.Mx
.It Ic ~H
Edit the message header fields
.Ql From: ,
.Ql Reply-To:
and
.Ql Sender:
by typing each one in turn and allowing the user to edit the field.
The default values for these fields originate from the
.Va from , replyto
and
.Va sender
variables.
.
.Mx
.It Ic ~h
Edit the message header fields
.Ql To: ,
.Ql Cc: ,
.Ql Bcc:
and
.Ql Subject:
by typing each one in turn and allowing the user to edit the field.
.
.Mx
.It Ic ~I Ar variable
Insert the value of the specified variable into the message.
The message remains unaltered if the variable is unset or empty.
\*(OB The escape sequences tabulator
.Ql \et
and newline
.Ql \en
are understood (use the
.Cm wysh
prefix when
.Ic set Ns
ting the variable(s) instead).
.
.Mx
.It Ic ~i Ar variable
Identical to
.Ic ~I ,
but adds a newline character at the end of a successful insertion.
.
.Mx
.It Ic ~M Ar messages
Read the named messages into the message being sent,
indented by
.Va indentprefix .
If no messages are specified, read the current message, the
.Dq dot .
.
.Mx
.It Ic ~m Ar messages
Read the named messages into the message being sent,
indented by
.Va indentprefix .
If no messages are specified, read the current message, the
.Dq dot .
Strips down the list of header fields according to the
.Ql type
white- and blacklist selection of
.Ic headerpick .
For MIME multipart messages,
only the first displayable part is included.
.
.Mx
.It Ic ~p
Display the message collected so far,
prefaced by the message header fields
and followed by the attachment list, if any.
.
.Mx
.It Ic ~q
Abort the message being sent,
copying it to the file specified by the
.Ev DEAD
variable if
.Va save
is set.
.
.Mx
.It Ic ~R Ar filename
Identical to
.Ic ~r ,
but indent each line that has been read by
.Va indentprefix .
.
.Mx
.It Ic ~r Ar filename Op Ar HERE-delimiter
Read the named file, object to the usual
.Sx "Filename transformations" ,
into the message; if (the expanded)
.Ar filename
is the hyphen-minus
.Ql -
then standard input is used, e.g., for pasting purposes.
Only in this latter mode
.Ar HERE-delimiter
may be given: if it is data will be read in until the given
.Ar HERE-delimiter
is seen on a line by itself, and encountering EOF is an error; the
.Ar HERE-delimiter
is a required argument in non-interactive mode; if it is single-quote
quoted then the pasted content will not be expanded, \*(ID otherwise
a future version of \*(UA may perform shell-style expansion on the content.
.
.Mx
.It Ic ~s Ar string
Cause the named string to become the current subject field.
Newline (NL) and carriage-return (CR) bytes are invalid and will be
normalized to space (SP) characters.
.
.Mx
.It Ic ~t Ar name ...
Add the given name(s) to the direct recipient list.
.
.Mx
.It Ic ~U Ar messages
Read in the given / current message(s) excluding all headers, indented by
.Va indentprefix .
.
.Mx
.It Ic ~u Ar messages
Read in the given / current message(s), excluding all headers.
.
.Mx
.It Ic ~v
Invoke an alternate editor (defined by the
.Ev VISUAL
environment variable) on the message collected so far.
Usually, the alternate editor will be a screen editor.
After the editor is quit,
the user may resume appending text to the end of the message.
.
.Mx
.It Ic ~w Ar filename
Write the message onto the named file, which is object to the usual
.Sx "Filename transformations" .
If the file exists,
the message is appended to it.
.
.Mx
.It Ic ~x
Same as
.Ic ~q ,
except that the message is not saved at all.
.
.Mx
.It Ic ~| Ar command
Pipe the message through the specified filter command.
If the command gives no output or terminates abnormally,
retain the original text of the message.
E.g., the command
.Xr fmt 1
is often used as a rejustifying filter.
.
.
.Mx
.It Ic ~^ Ar cmd Op Ar subcmd Op Ar arg3 Op Ar arg4
Low-level command meant for scripted message access, i.e., for
.Va on-compose-splice
and
.Va on-compose-splice-shell .
The used protocol is likely subject to changes, and therefore the
mentioned hooks receive the used protocol version as an initial line.
In general the first field of a response line represents a status code
which specifies whether a command was successful or not, whether result
data is to be expected, and if, the format of the result data.
Does not manage the error number
.Va \&!
and the exit status
.Va \&? ,
because errors are reported via the protocol
(hard errors like I/O failures cannot be handled).
This command has read-only access to several virtual pseudo headers in
the \*(UA private namespace, which may not exist (except for the first):
.
.
.Pp
.Bl -tag -compact -width ".It Va BaNg"
.It Ql Mailx-Command:
The name of the command that generates the message, one of
.Ql mail ,
.Ql reply ,
.Ql forward ,
.Ql resend .
.
.It Ql Mailx-Raw-To:
.It Ql Mailx-Raw-Cc:
.It Ql Mailx-Raw-Bcc:
Represent the frozen initial state of these headers before any
transformation (e.g.,
.Ic alias ,
.Ic alternates ,
.Va recipients-in-cc
etc.) took place.
.
.It Ql Mailx-Orig-From:
.It Ql Mailx-Orig-To:
.It Ql Mailx-Orig-Cc:
.It Ql Mailx-Orig-Bcc:
The values of said headers of the original message which has been
addressed by any of
.Ic reply , forward , resend .
.El
.
.Pp
The status codes are:
.
.
.Pp
.Bl -tag -compact -width ".It Ql 210"
.It Ql 210
Status ok; the remains of the line are the result.
.
.It Ql 211
Status ok; the rest of the line is optionally used for more status.
What follows are lines of result addresses, terminated by an empty line.
The address lines consist of two fields, the first of which is the
plain address, e.g.,
.Ql bob@exam.ple ,
separated by a single ASCII SP space from the second which contains the
unstripped address, even if that is identical to the first field, e.g.,
.Ql (Lovely) Bob <bob@exam.ple> .
All the input, including the empty line, must be consumed before further
commands can be issued.
.
.It Ql 212
Status ok; the rest of the line is optionally used for more status.
What follows are lines of furtherly unspecified string content,
terminated by an empty line.
All the input, including the empty line, must be consumed before further
commands can be issued.
.
.It Ql 500
Syntax error; invalid command.
.
.It Ql 501
Syntax error in parameters or arguments.
.
.It Ql 505
Error: an argument fails verification.
For example an invalid address has been specified, or an attempt was
made to modify anything in \*(UA's own namespace.
.
.It Ql 506
Error: an otherwise valid argument is rendered invalid due to context.
For example, a second address is added to a header which may consist of
a single address only.
.El
.
.
.Pp
If a command indicates failure then the message will have remained
unmodified.
Most commands can fail with
.Ql 500
if required arguments are missing (false command usage).
The following (case-insensitive) commands are supported:
.
.
.Bl -hang -width ".It Cm header"
.It Cm header
This command allows listing, inspection, and editing of message headers.
Header name case is not normalized, and case-insensitive comparison
should be used when matching names.
The second argument specifies the subcommand to apply, one of:
.
.Bl -hang -width ".It Cm remove"
.It Cm list
Without a third argument a list of all yet existing headers is given via
.Ql 210 ;
this command is the default command of
.Cm header
if no second argument has been given.
A third argument restricts output to the given header only, which may
fail with
.Ql 501
if no such field is defined.
.
.It Cm show
Shows the content of the header given as the third argument.
Dependent on the header type this may respond with
.Ql 211
or
.Ql 212 ;
any failure results in
.Ql 501 .
.
.It Cm remove
This will remove all instances of the header given as the third
argument, reporting
.Ql 210
upon success,
.Ql 501
if no such header can be found, and
Ql 505
on \*(UA namespace violations.
.
.It Cm remove-at
This will remove from the header given as the third argument the
instance at the list position (counting from one!) given with the fourth
argument, reporting
.Ql 210
upon success or
.Ql 505
if the list position argument is not a number or on \*(UA namespace
violations, and
.Ql 501
if no such header instance exists.
.
.It Cm insert
Create a new or an additional instance of the header given in the third
argument, with the header body content as given in the fourth argument
(the remains of the line).
It may return
.Ql 501
if the third argument specifies a free-form header field name that is
invalid, or if body content extraction fails to succeed,
.Ql 505
if any extracted address does not pass syntax and/or security checks or
on \*(UA namespace violations, and
.Ql 506
to indicate prevention of excessing a single-instance header \(em note that
.Ql Subject:
can be appended to (a space separator will be added automatically first).
.Pp
.Ql 210
is returned upon success, followed by the name of the header and the list
position of the newly inserted instance.
The list position is always 1 for single-instance header fields.
All free-form header fields are managed in a single list.
.El
.
.
.It Cm attachment
This command allows listing, removal and addition of message attachments.
The second argument specifies the subcommand to apply, one of:
.
.Bl -hang -width ".It Cm remove"
.It Cm list
List all attachments via
.Ql 212 ,
or report
.Ql 501
if no attachments exist.
This command is the default command of
.Cm attachment
if no second argument has been given.
.
.It Cm remove
This will remove the attachment given as the third argument, and report
.Ql 210
upon success or
.Ql 501
if no such attachment can be found.
If there exists any path component in the given argument, then an exact
match of the path which has been used to create the attachment is used
directly, but if only the basename of that path matches then all
attachments are traversed to find an exact match first, and the removal
occurs afterwards; if multiple basenames match, a
.Ql 506
error occurs.
Message attachments are treated as absolute pathnames.
.Pp
If no path component exists in the given argument, then all attachments
will be searched for
.Ql filename=
parameter matches as well as for matches of the basename of the path
which has been used when the attachment has been created; multiple
matches result in a
.Ql 506 .
.
.It Cm remove-at
This will interpret the third argument as a number and remove the
attachment at that list position (counting from one!), reporting
.Ql 210
upon success or
.Ql 505
if the argument is not a number or
.Ql 501
if no such attachment exists.
.
.It Cm insert
Adds the attachment given as the third argument, specified exactly as
documented for the command line option
.Fl a ,
and supporting the message number extension as documented for
.Ic ~@ .
This reports
.Ql 210
upon success, with the index of the new attachment following,
.Ql 505
if the given file cannot be opened,
.Ql 506
if an on-the-fly performed character set conversion fails, otherwise
.Ql 501
is reported; this is also reported if character set conversion is
requested but not available.
.
.It Cm attribute
This uses the same search mechanism as described for
.Cm remove
and prints any known attributes of the first found attachment via
.Ql 212
upon success or
.Ql 501
if no such attachment can be found.
The attributes are written as lines of keyword and value tuples, the
keyword being separated from the rest of the line with an ASCII SP space
character.
.
.It Cm attribute-at
This uses the same search mechanism as described for
.Cm remove-at
and is otherwise identical to
.Cm attribute .
.
.It Cm attribute-set
This uses the same search mechanism as described for
.Cm remove ,
and will assign the attribute given as the fourth argument, which is
expected to be a value tuple of keyword and other data, separated by
a ASCII SP space or TAB tabulator character.
If the value part is empty, then the given attribute is removed, or
reset to a default value if existence of the attribute is crucial.
.Pp
It returns via
.Ql 210
upon success, with the index of the found attachment following,
.Ql 505
for message attachments or if the given keyword is invalid, and
.Ql 501
if no such attachment can be found.
The following keywords may be used (case-insensitively):
.Pp
.Bl -hang -compact -width ".It Ql filename"
.It Ql filename
Sets the filename of the MIME part, i.e., the name that is used for
display and when (suggesting a name for) saving (purposes).
.It Ql content-description
Associate some descriptive information to the attachment's content, used
in favour of the plain filename by some MUAs.
.It Ql content-id
May be used for uniquely identifying MIME entities in several contexts;
this expects a special reference address format as defined in RFC 2045
and generates a
.Ql 505
upon address content verification failure.
.It Ql content-type
Defines the media type/subtype of the part, which is managed
automatically, but can be overwritten.
.It Ql content-disposition
Automatically set to the string
.Ql attachment .
.El
.
.It Cm attribute-set-at
This uses the same search mechanism as described for
.Cm remove-at
and is otherwise identical to
.Cm attribute-set .
.El
.El
.
.
.El
.
.\" }}}
.
.
.\" .Sh INTERNAL VARIABLES {{{
.Sh "INTERNAL VARIABLES"
.
Internal \*(UA variables are controlled via the
.Ic set
and
.Ic unset
commands; prefixing a variable name with the string
.Ql no
and calling
.Ic set
has the same effect as using
.Ic unset :
.Ql unset crt
and
.Ql set nocrt
do the same thing.
Creation or editing of variables can be performed in the
.Ev EDITOR
with the command
.Ic varedit .
.Ic varshow
will give more insight on the given variable(s), and
.Ic set ,
when called without arguments, will show a listing of all variables.
Both commands support a more
.Va verbose
listing mode.
Some well-known variables will also become inherited from the
program
.Sx ENVIRONMENT
implicitly, others can be imported explicitly with the command
.Ic environ
and henceforth share said properties.
.
.Pp
Two different kinds of internal variables exist.
There are boolean variables, which can only be in one of the two states
.Dq set
and
.Dq unset ,
and value variables with a(n optional) string value.
For the latter proper quoting is necessary upon assignment time, the
introduction of the section
.Sx COMMANDS
documents the supported quoting rules.
.
.Bd -literal -offset indent
? wysh set one=val\e 1 two="val 2" \e
    three='val "3"' four=$'val \e'4\e''; \e
    varshow one two three four; \e
    unset one two three four
.Ed
.
.Pp
Dependent upon the actual option the string values will be interpreted
as numbers, colour names, normal text etc., but there also exists
a special kind of string value, the
.Dq boolean string ,
which must either be a decimal integer (in which case
.Ql 0
is false and
.Ql 1
and any other value is true) or any of the (case-insensitive) strings
.Ql off ,
.Ql no ,
.Ql n
and
.Ql false
for a false boolean and
.Ql on ,
.Ql yes ,
.Ql y
and
.Ql true
for a true boolean; a special kind of boolean string is the
.Dq quadoption ,
which is a boolean string that can optionally be prefixed with the
(case-insensitive) term
.Ql ask- ,
as in
.Ql ask-yes ,
which causes prompting of the user in interactive mode, with the given
boolean as the default value.
.
.\" .Ss "Initial settings" {{{
.\" (Keep in SYNC: ./nail.h:okeys, ./nail.rc, ./nail.1:"Initial settings")
.Ss "Initial settings"
.
The standard POSIX 2008/Cor 2-2016 mandates the following initial
variable settings:
.Pf no Va allnet ,
.Pf no Va append ,
.Va asksub ,
.Pf no Va askbcc ,
.Pf no Va autoprint ,
.Pf no Va bang ,
.Pf no Va cmd ,
.Pf no Va crt ,
.Pf no Va debug ,
.Pf no Va dot ,
.Va escape
set to
.Ql ~ ,
.Pf no Va flipr ,
.Pf no Va folder ,
.Va header ,
.Pf no Va hold ,
.Pf no Va ignore ,
.Pf no Va ignoreeof ,
.Pf no Va keep ,
.Pf no Va keepsave ,
.Pf no Va metoo ,
.Pf no Va outfolder ,
.Pf no Va page ,
.Va prompt
set to
.Ql ?\0 ,
.Pf no Va quiet ,
.Pf no Va record ,
.Va save ,
.Pf no Va sendwait ,
.Pf no Va showto ,
.Pf no Va Sign ,
.Pf no Va sign ,
.Va toplines
set to
.Ql 5 .
.
.Pp
Notes: \*(UA does not support the
.Pf no Va onehop
variable \(en use command line options or
.Va mta-arguments
to pass options through to a
.Va mta .
And the default global
.Pa \*(UR
file, which is loaded unless the
.Fl \&:
(with according argument) or
.Fl n
command line options have been used, or the
.Ev MAILX_NO_SYSTEM_RC
environment variable is set (see
.Sx "Resource files" )
bends those initial settings a bit, e.g., it sets the variables
.Va hold ,
.Va keepsave
and
.Va keep ,
to name a few, establishes a default
.Ic headerpick
selection etc., and should thus be taken into account.
.\" }}}
.
.\" .Ss "Variables" {{{
.Ss "Variables"
.
.Bl -tag -width ".It Va BaNg"
.
.Mx
.It Va \&?
\*(RO The exit status of the last command, or the
.Ic return
value of the macro
.Ic call Ns
ed last.
This status has a meaning in the state machine: in conjunction with
.Va errexit
any non-0 exit status will cause a program exit, and in
.Ev POSIXLY_CORRECT
mode any error while loading (any of the) resource files will have the
same effect.
.Cm ignerr ,
one of the
.Sx "Command modifiers" ,
can be used to instruct the state machine to ignore errors.
.
.Mx
.It Va \&!
\*(RO The current error number
.Pf ( Xr errno 3 ) ,
which is set after an error occurred; it is also available via
.Va ^ERR ,
and the error name and documentation string can be queried via
.Va ^ERRNAME
and
.Va ^ERRDOC .
\*(ID This machinery is new and the error number is only really usable
if a command explicitly states that it manages the variable
.Va \&! ,
for others errno will be used in case of errors, or
.Va ^ERR Ns -INVAL
if that is 0: it thus may or may not reflect the real error.
The error number may be set with the command
.Ic return .
.
.
.Mx
.It Va ^
\*(RO This is a multiplexer variable which performs dynamic expansion of
the requested state or condition, of which there are:
.
.Pp
.Bl -tag -compact -width ".It Va BaNg"
.Mx
.Mx
.Mx
.It Va ^ERR , ^ERRDOC , ^ERRNAME
The number, documentation, and name of the current
.Xr errno 3 ,
respectively, which is usually set after an error occurred.
\*(ID This machinery is new and is usually reliable only if a command
explicitly states that it manages the variable
.Va \&! ,
which is effectively identical to
.Va \&\&^ERR .
Each of those variables can be suffixed with a hyphen minus followed by
a name or number, in which case the expansion refers to the given error.
Note this is a direct mapping of (a subset of) the system error values:
.Bd -literal -offset indent
define work {
  eval echo \e$1: \e$^ERR-$1: \e$^ERRNAME-$1: \e$^ERRDOC-$1
  vput vexpr i + "$1" 1
  if [ $i -lt 16 ]
    \excall work $i
  end
}
call work 0
.Ed
.El
.
.
.Mx
.It Va *
\*(RO Expands all positional parameters (see
.Va 1 ) ,
separated by a space character.
\*(ID The special semantics of the equally named special parameter of the
.Xr sh 1
are not yet supported.
.
.Mx
.It Va @
\*(RO Expands all positional parameters (see
.Va 1 ) ,
separated by a space character.
If placed in double quotation marks, each positional parameter is
properly quoted to expand to a single parameter again.
.
.Mx
.It Va #
\*(RO Expands to the number of positional parameters, i.e., the size of
the positional parameter stack in decimal.
.
.Mx
.It Va \&0
\*(RO Inside the scope of a
.Ic define Ns
d and
.Ic call Ns
ed macro this expands to the name of the calling macro, or to the empty
string if the macro is running from top-level.
For the \*(OPal regular expression search and replace operator of
.Ic vexpr
this expands to the entire matching expression.
It represents the program name in global context.
.
.Mx
.It Va 1
\*(RO Access of the positional parameter stack.
All further parameters can be accessed with this syntax, too, e.g.,
.Ql 2 ,
.Ql 3
etc.; positional parameters can be shifted off the stack by calling
.Ic shift .
The parameter stack contains, e.g., the arguments of a
.Ic call Ns
ed
.Ic define Ns
d macro, the matching groups of the \*(OPal regular expression search
and replace expression of
.Ic vexpr ,
and can be explicitly created or overwritten with the command
.Ic vpospar .
.
.Mx
.It Va account
\*(RO Is set to the active
.Ic account .
.
.Mx
.It Va add-file-recipients
\*(BO When file or pipe recipients have been specified,
mention them in the corresponding address fields of the message instead
of silently stripping them from their recipient list.
By default such addressees are not mentioned.
.
.Mx
.It Va allnet
\*(BO Causes only the local part to be evaluated
when comparing addresses.
.
.Mx
.It Va append
\*(BO Causes messages saved in the
.Mx -sx
.Sx "secondary mailbox"
.Ev MBOX
to be appended to the end rather than prepended.
This should always be set.
.
.Mx
.It Va ask
\*(BO Causes \*(UA to prompt for the subject of each message sent.
If the user responds with simply a newline,
no subject field will be sent.
.
.Mx
.It Va askatend
\*(BO Causes the prompts for
.Ql Cc:
and
.Ql Bcc:
lists to appear after the message has been edited.
.
.Mx
.It Va askattach
\*(BO If set, \*(UA asks for files to attach at the end of each message,
shall the list be found empty at that time.
An empty line finalizes the list.
.
.Mx
.It Va askcc
\*(BO Causes the user to be prompted for carbon copy recipients
(at the end of each message if
.Va askatend
or
.Va bsdcompat
are set) shall the list be found empty (at that time).
An empty line finalizes the list.
.
.Mx
.It Va askbcc
\*(BO Causes the user to be prompted for blind carbon copy
recipients (at the end of each message if
.Va askatend
or
.Va bsdcompat
are set) shall the list be found empty (at that time).
An empty line finalizes the list.
.
.Mx
.It Va asksign
\*(BO\*(OP Causes the user to be prompted if the message is to be
signed at the end of each message.
The
.Va smime-sign
variable is ignored when this variable is set.
.
.Mx
.It Va asksub
\*(BO Alternative name for
.Va ask .
.
.Mx
.It Va attrlist
A sequence of characters to display in the
.Ql attribute
column of the
.Va headline
as shown in the display of
.Ic headers ;
each for one type of messages (see
.Sx "Message states" ) ,
with the default being
.Ql NUROSPMFAT+\-$~
or
.Ql NU\ \ *HMFAT+\-$~
if the
.Va bsdflags
variable is set, in the following order:
.Pp
.Bl -tag -compact -width ".It Ql _"
.It Ql N
new.
.It Ql U
unread but old.
.It Ql R
new but read.
.It Ql O
read and old.
.It Ql S
saved.
.It Ql P
preserved.
.It Ql M
mboxed.
.It Ql F
flagged.
.It Ql A
answered.
.It Ql T
draft.
.It Ql +
start of a collapsed thread.
.It Ql -
an uncollapsed thread (TODO ignored for now).
.It Ql $
classified as spam.
.It Ql ~
classified as possible spam.
.El
.
.
.Mx
.It Va autobcc
Specifies a list of recipients to which a blind carbon copy of each
outgoing message will be sent automatically.
.
.Mx
.It Va autocc
Specifies a list of recipients to which a carbon copy of each outgoing
message will be sent automatically.
.
.Mx
.It Va autocollapse
\*(BO Causes threads to be collapsed automatically when threaded mode
is entered (see the
.Ic collapse
command).
.
.Mx
.It Va autoprint
\*(BO Enable automatic
.Ic type Ns
ing of a(n existing)
.Dq successive
message after
.Ic delete
and
.Ic undelete
commands, e.g., the message that becomes the new
.Dq dot
is shown automatically, as via
.Ic dp
or
.Ic dt .
.
.Mx
.It Va autosort
Causes sorted mode (see the
.Ic sort
command) to be entered automatically with the value of this variable as
sorting method when a folder is opened, e.g.,
.Ql set autosort=thread .
.
.Mx
.It Va bang
\*(BO Enables the substitution of all not (reverse-solidus) escaped
exclamation mark
.Ql \&!
characters by the contents of the last executed command for the
.Ic \&!
shell escape command and
.Ic ~! ,
one of the compose mode
.Sx "COMMAND ESCAPES" .
If this variable is not set no reverse solidus stripping is performed.
.
.Mx
.It Va bind-timeout
\*(OP Terminals generate multi-byte sequences for certain forms of
input, for example for function and other special keys.
Some terminals however do not write these multi-byte sequences as
a whole, but byte-by-byte, and the latter is what \*(UA actually reads.
This variable specifies the timeout in milliseconds that the MLE (see
.Sx "On terminal control and line editor" )
waits for more bytes to arrive unless it considers a sequence
.Dq complete .
The default is 200.
.
.Mx
.It Va bsdcompat
\*(BO Sets some cosmetical features to traditional BSD style;
has the same affect as setting
.Va askatend
and all other variables prefixed with
.Ql bsd ;
it also changes the behaviour of
.Va emptystart
(which does not exist in BSD).
.
.Mx
.It Va bsdflags
\*(BO Changes the letters shown in the first column of a header
summary to traditional BSD style.
.
.Mx
.It Va bsdheadline
\*(BO Changes the display of columns in a header summary to traditional
BSD style.
.
.Mx
.It Va bsdmsgs
\*(BO Changes some informational messages to traditional BSD style.
.
.Mx
.It Va bsdorder
\*(BO Causes the
.Ql Subject:
field to appear immediately after the
.Ql To:
field in message headers and with the
.Ic ~h
.Sx "COMMAND ESCAPES" .
.
.Mx
.Mx
.It Va build-os , build-osenv
\*(RO The operating system \*(UA has been build for, usually taken from
.Xr uname 1
via
.Ql uname -s
and
.Ql uname -srm ,
respectively, the former being lowercased.
.
.Mx
.It Va charset-7bit
The value that should appear in the
.Ql charset=
parameter of
.Ql Content-Type:
MIME header fields when no character set conversion of the message data
was performed.
This defaults to US-ASCII, and the chosen character set should be
US-ASCII compatible.
.
.Mx
.It Va charset-8bit
\*(OP The default 8-bit character set that is used as an implicit last
member of the variable
.Va sendcharsets .
This defaults to UTF-8 if character set conversion capabilities are
available, and to ISO-8859-1 otherwise, in which case the only supported
character set is
.Va ttycharset
and this variable is effectively ignored.
Refer to the section
.Sx "Character sets"
for the complete picture of character set conversion in \*(UA.
.
.Mx
.It Va charset-unknown-8bit
\*(OP RFC 1428 specifies conditions when internet mail gateways shall
.Dq upgrade
the content of a mail message by using a character set with the name
.Ql unknown-8bit .
Because of the unclassified nature of this character set \*(UA will not
be capable to convert this character set to any other character set.
If this variable is set any message part which uses the character set
.Ql unknown-8bit
is assumed to really be in the character set given in the value,
otherwise the (final) value of
.Va charset-8bit
is used for this purpose.
.Pp
This variable will also be taken into account if a MIME type (see
.Sx "The mime.types files" )
of a MIME message part that uses the
.Ql binary
character set is forcefully treated as text.
.
.Mx
.It Va cmd
The default value for the
.Ic pipe
command.
.
.Mx
.It Va colour-disable
\*(BO\*(OP Forcefully disable usage of colours.
Also see the section
.Sx "Coloured display" .
.
.Mx
.It Va colour-pager
\*(BO\*(OP Whether colour shall be used for output that is paged through
.Ev PAGER .
Note that pagers may need special command line options, e.g.,
.Xr less 1
requires the option
.Fl \&\&R
and
.Xr lv 1
the option
.Fl \&\&c
in order to support colours.
Often doing manual adjustments is unnecessary since \*(UA may perform
adjustments dependent on the value of the environment variable
.Ev PAGER
(see there for more).
.
.Mx
.Mx
.It Va contact-mail , contact-web
\*(RO Addresses for contact per email and web, respectively, e.g., for
bug reports, suggestions, or help regarding \*(UA.
The former can be used directly:
.Ql ? eval mail $contact-mail .
.
.Mx
.It Va crt
In a(n interactive) terminal session, then if this valued variable is
set it will be used as a threshold to determine how many lines the given
output has to span before it will be displayed via the configured
.Ev PAGER ;
Usage of the
.Ev PAGER
can be forced by setting this to the value
.Ql 0 ,
setting it without a value will deduce the current height of the
terminal screen to compute the treshold (see
.Ev LINES ,
.Va screen
and
.Xr stty 1 ) .
\*(ID At the moment this uses the count of lines of the message in wire
format, which, dependent on the
.Va mime-encoding
of the message, is unrelated to the number of display lines.
(The software is old and historically the relation was a given thing.)
.
.Mx
.It Va customhdr
Define a set of custom headers to be injected into newly composed or
forwarded messages; it is also possible to create custom headers in
compose mode with
.Ic ~^ ,
which can be automated by setting one of the hooks
.Va on-compose-splice
or
.Va on-compose-splice-shell .
The value is interpreted as a comma-separated list of custom headers to
be injected, to include commas in the header bodies escape them with
reverse solidus.
\*(ID Overwriting of automatically managed headers is neither supported
nor prevented.
.Pp
.Dl ? set customhdr='Hdr1: Body1-1\e, Body1-2,  Hdr2: Body2'
.
.Mx
.It Va datefield
Controls the appearance of the
.Ql %d
date and time format specification of the
.Va headline
variable, that is used, for example, when viewing the summary of
.Ic headers .
If unset, then the local receiving date is used and displayed
unformatted, otherwise the message sending
.Ql Date: .
It is possible to assign a
.Xr strftime 3
format string and control formatting, but embedding newlines via the
.Ql %n
format is not supported, and will result in display errors.
The default is
.Ql %Y-%m-%d %H:%M ,
and also see
.Va datefield-markout-older .
.
.Mx
.It Va datefield-markout-older
Only used in conjunction with
.Va datefield .
Can be used to create a visible distinction of messages dated more than
a day in the future, or older than six months, a concept comparable to the
.Fl \&\&l
option of the POSIX utility
.Xr ls 1 .
If set to the empty string, then the plain month, day and year of the
.Ql Date:
will be displayed, but a
.Xr strftime 3
format string to control formatting can be assigned.
The default is
.Ql %Y-%m-%d .
.
.Mx
.It Va debug
\*(BO Enables debug messages and obsoletion warnings, disables the
actual delivery of messages and also implies
.Pf no Va record
as well as
.Pf no Va save .
.
.Mx
.It Va disposition-notification-send
\*(BO\*(OP Emit a
.Ql Disposition-Notification-To:
header (RFC 3798) with the message.
This requires the
.Va from
variable to be set.
.\" TODO .It Va disposition-notification-send-HOST
.\"Overrides
.\".Va disposition-notification-send
.\" for SMTP accounts on a specific host.
.\" TODO .It Va disposition-notification-send-USER@HOST
.\"Overrides
.\".Va disposition-notification-send
.\"for a specific account.
.
.Mx
.It Va dot
\*(BO When dot is set, a period
.Ql \&.
on a line by itself during message input in (interactive or batch
.Fl # )
compose mode will be treated as end-of-message (in addition to the
normal end-of-file condition).
This behaviour is implied in
.Va posix
mode with a set
.Va ignoreeof .
.
.Mx
.It Va dotlock-ignore-error
\*(BO\*(OP Synchronization of mailboxes which \*(UA treats as
.Mx -sx
.Sx "primary system mailbox" Ns
es (see, e.g., the notes on
.Sx "Filename transformations" ,
as well as the documentation of
.Ic file )
will be protected with so-called dotlock files\(emthe traditional mail
spool file locking method\(emin addition to system file locking.
Because \*(UA ships with a privilege-separated dotlock creation program
that should always be able to create such a dotlock file there is no
good reason to ignore dotlock file creation errors, and thus these are
fatal unless this variable is set.
.
.Mx
.It Va editalong
\*(BO If this variable is set then the editor is started automatically
when a message is composed in interactive mode, as if the
.Ic ~e
.Sx "COMMAND ESCAPES"
had been specified.
The
.Va editheaders
variable is implied for this automatically spawned editor session.
.
.Mx
.It Va editheaders
\*(BO When a message is edited while being composed,
its header is included in the editable text.
.
.Mx
.It Va emptystart
\*(BO When entering interactive mode \*(UA normally writes
.Dq \&No mail for user
and exits immediately if a mailbox is empty or does not exist.
If this variable is set \*(UA starts even with an empty or non-existent
mailbox (the latter behaviour furtherly depends upon
.Va bsdcompat ,
though).
.
.Mx
.It Va errexit
\*(BO Let each command with a non-0 exit status, including every
.Ic call Ns
ed macro which
.Ic return Ns
s a non-0 status, cause a program exit unless prefixed by
.Cm ignerr
(see
.Sx "Command modifiers" ) .
This also affects
.Sx "COMMAND ESCAPES" ,
but which use a different modifier for ignoring the error.
Please refer to the variable
.Va \&?
for more on this topic.
.
.Mx
.It Va escape
The first character of this value defines the escape character for
.Sx "COMMAND ESCAPES"
in compose mode.
The default value is the character tilde
.Ql ~ .
If set to the empty string, command escapes are disabled.
.
.Mx
.It Va expandaddr
If not set then file and command pipeline targets are not allowed,
and any such address will be filtered out, giving a warning message.
If set without a value then all possible recipient address
specifications will be accepted \(en see the section
.Sx "On sending mail, and non-interactive mode"
for more on this.
To accept them, but only in interactive mode, or when tilde commands
were enabled explicitly by using one of the command line options
.Fl ~
or
.Fl # ,
set this to the (case-insensitive) value
.Ql restrict
(it actually acts like
.Ql restrict,-all,+name,+addr ,
so that care for ordering issues must be taken) .
.Pp
In fact the value is interpreted as a comma-separated list of values.
If it contains
.Ql fail
then the existence of disallowed specifications is treated as a hard
send error instead of only filtering them out.
The remaining values specify whether a specific type of recipient
address specification is allowed (optionally indicated by a plus sign
.Ql +
prefix) or disallowed (prefixed with a hyphen-minus
.Ql - ) .
The value
.Ql all
addresses all possible address specifications,
.Ql file
file targets,
.Ql pipe
command pipeline targets,
.Ql name
plain user names and (MTA) aliases and
.Ql addr
network addresses.
These kind of values are interpreted in the given order, so that
.Ql restrict,\:fail,\:+file,\:-all,\:+addr
will cause hard errors for any non-network address recipient address
unless \*(UA is in interactive mode or has been started with the
.Fl ~
or
.Fl #
command line option; in the latter case(s) any address may be used, then.
.Pp
Historically invalid network addressees are silently stripped off.
To change this so that any encountered invalid email address causes
a hard error it must be ensured that
.Ql failinvaddr
is an entry in the above list.
Setting this automatically enables network addressees
(it actually acts like
.Ql failinvaddr,+addr ,
so that care for ordering issues must be taken) .
.
.Mx
.It Va expandargv
Unless this variable is set additional
.Va mta
(Mail-Transfer-Agent)
arguments from the command line, as can be given after a
.Fl \&\&-
separator, are ignored due to safety reasons.
However, if set to the special (case-insensitive) value
.Ql fail ,
then the presence of additional MTA arguments is treated as a hard
error that causes \*(UA to exit with failure status.
A lesser strict variant is the otherwise identical
.Ql restrict ,
which does accept such arguments in interactive mode, or if tilde
commands were enabled explicitly by using one of the command line options
.Fl ~
or
.Fl # .
.
.Mx
.It Va features
\*(RO String giving a list of features \*(UA, preceded with a plus sign
.Ql +
if the feature is available, and a hyphen-minus
.Ql -
otherwise.
The output of the command
.Ic version
will include this information in a more pleasant output.
.
.Mx
.It Va flipr
\*(BO This setting reverses the meanings of a set of reply commands,
turning the lowercase variants, which by default address all recipients
included in the header of a message
.Pf ( Ic reply , respond , followup )
into the uppercase variants, which by default address the sender only
.Pf ( Ic Reply , Respond , Followup )
and vice versa.
The commands
.Ic replysender , respondsender , followupsender
as well as
.Ic replyall , respondall , followupall
are not affected by the current setting of
.Va flipr .
.
.Mx
.It Va folder
The default path under which mailboxes are to be saved:
filenames that begin with the plus sign
.Ql +
will have the plus sign replaced with the value of this variable if set,
otherwise the plus sign will remain unchanged when doing
.Sx "Filename transformations" ;
also see
.Ic file
for more on this topic.
The value supports a subset of transformations itself, and if the
non-empty value does not start with a solidus
.Ql / ,
then the value of
.Ev HOME
will be prefixed automatically.
Once the actual value is evaluated first, the internal variable
.Va folder-resolved
will be updated for caching purposes.
.
.Mx
.It Va folder-hook
This variable can be set to the name of a
.Ic define Ns d
macro which will be called whenever a
.Ic file
is opened.
The macro will also be invoked when new mail arrives,
but message lists for commands executed from the macro
only include newly arrived messages then.
.Ic localopts
are activated by default in a folder hook, causing the covered settings
to be reverted once the folder is left again.
.
.Mx
.It Va folder-hook-FOLDER
Overrides
.Va folder-hook
for a folder named
.Ql FOLDER .
Unlike other folder specifications, the fully expanded name of a folder,
without metacharacters, is used to avoid ambiguities.
However, if the mailbox resides under
.Va folder
then the usual
.Ql +
specification is tried in addition, e.g., if
.Va \&\&folder
is
.Dq mail
(and thus relative to the user's home directory) then
.Pa /home/usr1/mail/sent
will be tried as
.Ql folder-hook-/home/usr1/mail/sent
first, but then followed by
.Ql folder-hook-+sent .
.
.Mx
.It Va folder-resolved
\*(RO Set to the fully resolved path of
.Va folder
once that evaluation has occurred; rather internal.
.
.Mx
.It Va followup-to
\*(BO Controls whether a
.Ql Mail-Followup-To:
header is generated when sending messages to known mailing lists.
Also see
.Va followup-to-honour
and the commands
.Ic mlist , mlsubscribe , reply
and
.Ic Lreply .
.
.Mx
.It Va followup-to-honour
Controls whether a
.Ql Mail-Followup-To:
header is honoured when group-replying to a message via
.Ic reply
or
.Ic Lreply .
This is a quadoption; if set without a value it defaults to
.Dq yes .
Also see
.Va followup-to
and the commands
.Ic mlist
and
.Ic mlsubscribe .
.
.Mx
.It Va forward-as-attachment
\*(BO Original messages are normally sent as inline text with the
.Ic forward
command,
and only the first part of a multipart message is included.
With this setting enabled messages are sent as unmodified MIME
.Ql message/rfc822
attachments with all of their parts included.
.
.Mx
.It Va forward-inject-head
The string to put before the text of a message with the
.Ic forward
command instead of the default
.Dq -------- Original Message -------- .
No heading is put if it is set to the empty string.
This variable is ignored if the
.Va forward-as-attachment
variable is set.
.
.Mx
.It Va from
The address (or a list of addresses) to put into the
.Ql From:
field of the message header, quoting RFC 5322:
the author(s) of the message, that is, the mailbox(es) of the person(s)
or system(s) responsible for the writing of the message.
When
.Ic reply Ns
ing to messages these addresses are handled as if they were in the
.Ic alternates
list.
.Pp
If the machine's hostname is not valid at the Internet (for example at
a dialup machine) then either this variable or
.Va hostname
(\*(IN and with a defined SMTP protocol in
.Va mta
.Va smtp-hostname
adds even more fine-tuning capabilities),
have to be set.
If
.Va \&\&from
contains more than one address,
setting the
.Va sender
variable is required (according to the standard RFC 5322).
.Pp
If a file-based MTA is used, then
.Va from
(or, if that contains multiple addresses,
.Va sender )
can nonetheless be enforced to appear as the envelope sender address at
the MTA protocol level (the RFC 5321 reverse-path), either by using the
.Fl r
command line option (with an empty argument; see there for the complete
picture on this topic), or by setting the internal variable
.Va r-option-implicit .
.
.Mx
.It Va fullnames
\*(BO When replying to or forwarding a message \*(UA normally removes
the comment and name parts of email addresses.
If this variable is set such stripping is not performed,
and comments, names etc. are retained.
.
.It Va fwdheading
\*(OB Predecessor of
.Va forward-inject-head .
.
.Mx
.It Va header
\*(BO Causes the header summary to be written at startup and after
commands that affect the number of messages or the order of messages in
the current
.Ic folder .
Unless in
.Ev POSIXLY_CORRECT
mode a header summary will also be displayed on folder changes.
The command line option
.Fl N
can be used to set
.Pf no Va header .
.
.
.Mx
.It Va headline
A format string to use for the summary of
.Ic headers ,
similar to the ones used for
.Xr printf 3
formats.
Format specifiers in the given string start with a percent sign
.Ql %
and may be followed by an optional decimal number indicating the field
width \(em if that is negative, the field is to be left-aligned.
Valid format specifiers are:
.
.Pp
.Bl -tag -compact -width ".It Ql _%%_"
.It Ql %%
A plain percent sign.
.It Ql %>
.Dq Dotmark :
a space character but for the current message
.Pf ( Dq dot ) ,
for which it expands to
.Ql > .
.It Ql %<
.Dq Dotmark :
a space character but for the current message
.Pf ( Dq dot ) ,
for which it expands to
.Ql < .
.It Ql %$
\*(OP The spam score of the message, as has been classified via the
command
.Ic spamrate .
Shows only a replacement character if there is no spam support.
.It Ql %a
Message attribute character (status flag); the actual content can be
adjusted by setting
.Va attrlist .
.It Ql %d
The date found in the
.Ql From:
header of the message when
.Va datefield
is set (the default), otherwise the date when the message was received.
Formatting can be controlled by assigning a
.Xr strftime 3
format string to
.Va datefield .
.It Ql %e
The indenting level in threaded mode.
.It Ql %f
The address of the message sender.
.It Ql %i
The message thread tree structure.
(Note that this format does not support a field width.)
.It Ql %l
The number of lines of the message, if available.
.It Ql %m
Message number.
.It Ql %o
The number of octets (bytes) in the message, if available.
.It Ql %s
Message subject (if any).
.It Ql %S
Message subject (if any) in double quotes.
.It Ql \&%T
Message recipient flags: is the addressee of the message a known or
subscribed mailing list \(en see
.Ic mlist
and
.Ic mlsubscribe .
.It Ql %t
The position in threaded/sorted order.
.El
.Pp
The default is
.Ql %>\&%a\&%m\ %-18f\ %16d\ %4l/%\-5o\ %i%-s ,
or
.Ql %>\&%a\&%m\ %20-f\ \ %16d\ %3l/%\-5o\ %i%-S
if
.Va bsdcompat
is set.
Also see
.Va attrlist
and
.Va headline-bidi .
.
.
.Mx
.It Va headline-bidi
Bidirectional text requires special treatment when displaying headers,
because numbers (in dates or for file sizes etc.) will not affect the
current text direction, in effect resulting in ugly line layouts when
arabic or other right-to-left text is to be displayed.
On the other hand only a minority of terminals is capable to correctly
handle direction changes, so that user interaction is necessary for
acceptable results.
Note that extended host system support is required nonetheless, e.g.,
detection of the terminal character set is one precondition;
and this feature only works in an Unicode (i.e., UTF-8) locale.
.Pp
In general setting this variable will cause \*(UA to encapsulate text
fields that may occur when displaying
.Va headline
(and some other fields, like dynamic expansions in
.Va prompt )
with special Unicode control sequences;
it is possible to fine-tune the terminal support level by assigning
a value:
no value (or any value other than
.Ql 1 ,
.Ql 2
and
.Ql 3 )
will make \*(UA assume that the terminal is capable to properly deal
with Unicode version 6.3, in which case text is embedded in a pair of
U+2068 (FIRST STRONG ISOLATE) and U+2069 (POP DIRECTIONAL ISOLATE)
characters.
In addition no space on the line is reserved for these characters.
.Pp
Weaker support is chosen by using the value
.Ql 1
(Unicode 6.3, but reserve the room of two spaces for writing the control
sequences onto the line).
The values
.Ql 2
and
.Ql 3
select Unicode 1.1 support (U+200E, LEFT-TO-RIGHT MARK); the latter
again reserves room for two spaces in addition.
.
.Mx
.It Va history-file
\*(OP If a line editor is available then this can be set to
name the (expandable) path of the location of a permanent history file.
Also see
.Va history-size .
.
.Mx
.It Va history-gabby
\*(BO\*(OP Add more entries to the history as is normally done.
.
.Mx
.It Va history-gabby-persist
\*(BO\*(OP \*(UA's own MLE will not save the additional
.Va history-gabby
entries in persistent storage unless this variable is set.
On the other hand it will not loose the knowledge of whether
a persistent entry was gabby or not.
Also see
.Va history-file .
.
.Mx
.It Va history-size
\*(OP Setting this variable imposes a limit on the number of concurrent
history entries.
If set to the value 0 then no further history entries will be added, and
loading and incorporation of the
.Va history-file
upon program startup can also be suppressed by doing this.
Runtime changes will not be reflected, but will affect the number of
entries saved to permanent storage.
.
.Mx
.It Va hold
\*(BO This setting controls whether messages are held in the system
.Va inbox ,
and it is set by default.
.
.Mx
.It Va hostname
Use this string as hostname when expanding local addresses instead of
the value obtained from
.Xr uname 3
and
.Xr getaddrinfo 3 .
It is used, e.g., in
.Ql Message-ID:
and
.Ql From:
fields, as well as when generating
.Ql Content-ID:
MIME part related unique ID fields.
Setting it to the empty string will cause the normal hostname to be
used, but nonetheless enables creation of said ID fields.
\*(IN in conjunction with the built-in SMTP
.Va mta
.Va smtp-hostname
also influences the results:
one should produce some test messages with the desired combination of
.Va \&\&hostname ,
and/or
.Va from ,
.Va sender
etc. first.
.
.Mx
.It Va idna-disable
\*(BO\*(OP Can be used to turn off the automatic conversion of domain
names according to the rules of IDNA (internationalized domain names
for applications).
Since the IDNA code assumes that domain names are specified with the
.Va ttycharset
character set, an UTF-8 locale charset is required to represent all
possible international domain names (before conversion, that is).
.
.Mx
.It Va ifs
The input field separator that is used (\*(ID by some functions) to
determine where to split input data.
.Pp
.Bl -tag -compact -width ".It MMM"
.It 1.
Unsetting is treated as assigning the default value,
.Ql \& \et\en .
.It 2.
If set to the empty value, no field splitting will be performed.
.It 3.
If set to a non-empty value, all whitespace characters are extracted
and assigned to the variable
.Va ifs-ws .
.El
.Pp
.Bl -tag -compact -width ".It MMM"
.It a.
.Va \&\&ifs-ws
will be ignored at the beginning and end of input.
Diverging from POSIX shells default whitespace is removed in addition,
which is owed to the entirely different line content extraction rules.
.It b.
Each occurrence of a character of
.Va \&\&ifs
will cause field-splitting, any adjacent
.Va \&\&ifs-ws
characters will be skipped.
.El
.
.Mx
.It Va ifs-ws
\*(RO Automatically deduced from the whitespace characters in
.Va ifs .
.
.Mx
.It Va ignore
\*(BO Ignore interrupt signals from the terminal while entering
messages; instead echo them as
.Ql @
characters and discard the current line.
.
.Mx
.It Va ignoreeof
\*(BO Ignore end-of-file conditions
.Pf ( Ql control-D )
in compose mode on message input and in interactive command input.
If set an interactive command input session can only be left by
explicitly using one of the commands
.Ic exit
and
.Ic quit ,
and message input in compose mode can only be terminated by entering
a period
.Ql \&.
on a line by itself or by using the
.Ic ~.
.Sx "COMMAND ESCAPES" ;
Setting this implies the behaviour that
.Va dot
describes in
.Va posix
mode.
.
.Mx
.It Va inbox
If this is set to a non-empty string it will specify the users
.Mx -sx
.Sx "primary system mailbox" ,
overriding
.Ev MAIL
and the system-dependent default, and (thus) be used to replace
.Ql %
when doing
.Sx "Filename transformations" ;
also see
.Ic file
for more on this topic.
The value supports a subset of transformations itself.
.
.Mx
.It Va indentprefix
String used by the
.Ic ~m , ~M
and
.Ic ~R
.Sx "COMMAND ESCAPES"
and by the
.Va quote
option for indenting messages,
in place of the normal tabulator character
.Ql ^I ,
which is the default.
Be sure to quote the value if it contains spaces or tabs.
.
.Mx
.It Va keep
\*(BO If set, an empty
.Mx -sx
.Sx "primary system mailbox"
file is not removed.
Note that, in conjunction with
.Ev POSIXLY_CORRECT
any empty file will be removed unless this variable is set.
This may improve the interoperability with other mail user agents
when using a common folder directory, and prevents malicious users
from creating fake mailboxes in a world-writable spool directory.
\*(ID Only local regular (MBOX) files are covered, Maildir or other
mailbox types will never be removed, even if empty.
.
.Mx
.It Va keep-content-length
\*(BO When (editing messages and) writing MBOX mailbox files \*(UA can
be told to keep the
.Ql Content-Length:
and
.Ql Lines:
header fields that some MUAs generate by setting this variable.
Since \*(UA does neither use nor update these non-standardized header
fields (which in itself shows one of their conceptual problems),
stripping them should increase interoperability in between MUAs that
work with with same mailbox files.
Note that, if this is not set but
.Va writebackedited ,
as below, is, a possibly performed automatic stripping of these header
fields already marks the message as being modified.
\*(ID At some future time \*(UA will be capable to rewrite and apply an
.Va mime-encoding
to modified messages, and then those fields will be stripped silently.
.
.Mx
.It Va keepsave
\*(BO When a message is saved it is usually discarded from the
originating folder when \*(UA is quit.
This setting causes all saved message to be retained.
.
.Mx
.It Va line-editor-disable
\*(BO Turn off any enhanced line editing capabilities (see
.Sx "On terminal control and line editor"
for more).
.
.Mx
.It Va line-editor-no-defaults
\*(BO\*(OP Do not establish any default key binding.
.
.Mx
.It Va log-prefix
Error log message prefix string
.Pf ( Ql "\*(uA: " ) .
.
.Mx
.It Va mailbox-display
\*(RO The name of the current mailbox
.Pf ( Ic file ) ,
possibly abbreviated for display purposes.
.
.Mx
.It Va mailbox-resolved
\*(RO The fully resolved path of the current mailbox.
.
.Mx
.It Va mailx-extra-rc
An additional startup file that is loaded as the last of the
.Sx "Resource files" .
Use this file for commands that are not understood by other POSIX
.Xr mailx 1
implementations, i.e., mostly anything which is not covered by
.Sx "Initial settings" .
.
.Mx
.It Va markanswered
\*(BO When a message is replied to and this variable is set,
it is marked as having been
.Ic answered .
See the section
.Sx "Message states" .
.
.Mx
.It Va mbox-rfc4155
\*(BO When opening MBOX mailbox databases \*(UA by default uses tolerant
POSIX rules for detecting message boundaries (so-called
.Ql From_
lines) due to compatibility reasons, instead of the stricter rules that
have been standardized in RFC 4155.
This behaviour can be switched to the stricter RFC 4155 rules by
setting this variable.
(This is never necessary for any message newly generated by \*(UA,
it only applies to messages generated by buggy or malicious MUAs, or may
occur in old MBOX databases: \*(UA itself will choose a proper
.Va mime-encoding
to avoid false interpretation of
.Ql From_
content lines in the MBOX database.)
.Pp
This may temporarily be handy when \*(UA complains about invalid
.Ql From_
lines when opening a MBOX: in this case setting this variable and
re-opening the mailbox in question may correct the result.
If so, copying the entire mailbox to some other file, as in
.Ql copy * SOME-FILE ,
will perform proper, all-compatible
.Ql From_
quoting for all detected messages, resulting in a valid MBOX mailbox.
Finally the variable can be unset again:
.Bd -literal -offset indent
define mboxfix {
  localopts yes; wysh set mbox-rfc4155;\e
    wysh File "${1}"; eval copy * "${2}"
}
call mboxfix /tmp/bad.mbox /tmp/good.mbox
.Ed
.
.Mx
.It Va memdebug
\*(BO Internal development variable.
.
.Mx
.It Va message-id-disable
\*(BO By setting this variable the generation of
.Ql Message-ID:
can be completely suppressed, effectively leaving this task up to the
.Va mta
(Mail-Transfer-Agent) or the SMTP server.
(According to RFC 5321 a SMTP server is not required to add this
field by itself, so it should be ensured that it accepts messages without
.Ql Message-ID . )
This variable also affects automatic generation of
.Va Content-ID:
MIME header fields.
.
.Mx
.It Va message-inject-head
A string to put at the beginning of each new message.
The escape sequences tabulator
.Ql \et
and newline
.Ql \en
are understood.
.
.Mx
.It Va message-inject-tail
A string to put at the end of each new message.
The escape sequences tabulator
.Ql \et
and newline
.Ql \en
are understood.
.
.Mx
.It Va metoo
\*(BO Usually, when an
.Ic alias
expansion contains the sender, the sender is removed from the expansion.
Setting this option suppresses these removals.
Note that a set
.Va metoo
also causes a
.Ql -m
option to be passed through to the
.Va mta
(Mail-Transfer-Agent); though most of the modern MTAs no longer document
this flag, no MTA is known which does not support it (for historical
compatibility).
.
.Mx
.It Va mime-allow-text-controls
\*(BO When sending messages, each part of the message is MIME-inspected
in order to classify the
.Ql Content-Type:
and
.Ql Content-Transfer-Encoding:
(see
.Va mime-encoding )
that is required to send this part over mail transport, i.e.,
a computation rather similar to what the
.Xr file 1
command produces when used with the
.Ql --mime
option.
.Pp
This classification however treats text files which are encoded in
UTF-16 (seen for HTML files) and similar character sets as binary
octet-streams, forcefully changing any
.Ql text/plain
or
.Ql text/html
specification to
.Ql application/octet-stream :
If that actually happens a yet unset charset MIME parameter is set to
.Ql binary ,
effectively making it impossible for the receiving MUA to automatically
interpret the contents of the part.
.Pp
If this variable is set, and the data was unambiguously identified as
text data at first glance (by a
.Ql .txt
or
.Ql .html
file extension), then the original
.Ql Content-Type:
will not be overwritten.
.
.Mx
.It Va mime-alternative-favour-rich
\*(BO If this variable is set then rich MIME alternative parts (e.g.,
HTML) will be preferred in favour of included plain text versions when
displaying messages, provided that a handler exists which produces
output that can be (re)integrated into \*(UA's normal visual display.
(E.g., at the time of this writing some newsletters ship their full
content only in the rich HTML part, whereas the plain text part only
contains topic subjects.)
.
.Mx
.It Va mime-counter-evidence
Normally the
.Ql Content-Type:
field is used to decide how to handle MIME parts.
Some MUAs, however, do not use
.Sx "The mime.types files"
(also see
.Sx "HTML mail and MIME attachments" )
or a similar mechanism to correctly classify content, but specify an
unspecific MIME type
.Pf ( Ql application/octet-stream )
even for plain text attachments.
If this variable is set then \*(UA will try to re-classify such MIME
message parts, if possible, for example via a possibly existing
attachment filename.
A non-empty value may also be given, in which case a number is expected,
actually a carrier of bits.
Creating the bit-carrying number is a simple addition:
.Bd -literal -offset indent
? !echo Value should be set to $((2 + 4 + 8))
Value should be set to 14
.Ed
.Pp
.Bl -bullet -compact
.It
If bit two is set (2) then the detected
.Ic mimetype
will be carried along with the message and be used for deciding which
MIME handler is to be used, for example;
when displaying such a MIME part the part-info will indicate the
overridden content-type by showing a plus sign
.Ql + .
.It
If bit three is set (4) then the counter-evidence is always produced
and a positive result will be used as the MIME type, even forcefully
overriding the parts given MIME type.
.It
If bit four is set (8) then as a last resort the actual content of
.Ql application/octet-stream
parts will be inspected, so that data which looks like plain text can be
treated as such.
.El
.
.Mx
.It Va mime-encoding
The MIME
.Ql Content-Transfer-Encoding
to use in outgoing text messages and message parts, where applicable.
(7-bit clean text messages are sent as-is, without a transfer encoding.)
Valid values are:
.Pp
.Bl -tag -compact -width ".It Ql _%%_"
.It Ql 8bit
.Pf (Or\0 Ql 8b . )
8-bit transport effectively causes the raw data be passed through
unchanged, but may cause problems when transferring mail messages over
channels that are not ESMTP (RFC 1869) compliant.
Also, several input data constructs are not allowed by the
specifications and may cause a different transfer-encoding to be used.
.It Ql quoted-printable
.Pf (Or\0 Ql qp . )
Quoted-printable encoding is 7-bit clean and has the property that ASCII
characters are passed through unchanged, so that an english message can
be read as-is; it is also acceptible for other single-byte locales that
share many characters with ASCII, like, e.g., ISO-8859-1.
The encoding will cause a large overhead for messages in other character
sets: e.g., it will require up to twelve (12) bytes to encode a single
UTF-8 character of four (4) bytes.
.It Ql base64
.Pf (Or\0 Ql b64 . )
The default encoding, it is 7-bit clean and will always be used for
binary data.
This encoding has a constant input:output ratio of 3:4, regardless of
the character set of the input data it will encode three bytes of input
to four bytes of output.
This transfer-encoding is not human readable without performing
a decoding step.
.El
.
.Mx
.It Va mimetypes-load-control
Can be used to control which of
.Sx "The mime.types files"
are loaded: if the letter
.Ql u
is part of the option value, then the user's personal
.Pa ~/.mime.types
file will be loaded (if it exists); likewise the letter
.Ql s
controls loading of the system wide
.Pa /etc/mime.types ;
directives found in the user file take precedence, letter matching is
case-insensitive.
If this variable is not set \*(UA will try to load both files.
Incorporation of the \*(UA-built-in MIME types cannot be suppressed,
but they will be matched last (the order can be listed via
.Ic mimetype ) .
.Pp
More sources can be specified by using a different syntax: if the
value string contains an equals sign
.Ql =
then it is instead parsed as a comma-separated list of the described
letters plus
.Ql f=FILENAME
pairs; the given filenames will be expanded and loaded, and their
content may use the extended syntax that is described in the section
.Sx "The mime.types files" .
Directives found in such files always take precedence (are prepended to
the MIME type cache).
.
.
.Mx
.It Va mta
To choose an alternate Mail-Transfer-Agent, set this option to either
the full pathname of an executable (optionally prefixed with a
.Ql file://
protocol indicator), or \*(OPally a SMTP protocol URL, e.g., \*(IN
.Pp
.Dl smtps?://[user[:password]@]server[:port]
.Pp
(\*(OU:
.Ql [smtp://]server[:port] . )
The default has been chosen at compile time.
All supported data transfers are executed in child processes, which
run asynchronously and without supervision unless either the
.Va sendwait
or the
.Va verbose
variable is set.
If such a child receives a TERM signal, it will abort and
.Va save
the message to
.Ev DEAD ,
if so configured.
.
.Pp
For a file-based MTA it may be necessary to set
.Va mta-argv0
in in order to choose the right target of a modern
.Xr mailwrapper 8
environment.
It will be passed command line arguments from several possible sources:
from the variable
.Va mta-arguments
if set, from the command line if given and the variable
.Va expandargv
allows their use.
Argument processing of the MTA will be terminated with a
.Fl \&\&-
separator.
.
.Pp
The otherwise occurring implicit usage of the following MTA command
line arguments can be disabled by setting the boolean variable
.Va mta-no-default-arguments
(which will also disable passing
.Fl \&\&-
to the MTA):
.Fl \&\&i
(for not treating a line with only a dot
.Ql \&.
character as the end of input),
.Fl \&\&m
(shall the variable
.Va metoo
be set) and
.Fl \&\&v
(if the
.Va verbose
variable is set); in conjunction with the
.Fl r
command line option \*(UA will also (not) pass
.Fl \&\&f
as well as possibly
.Fl \&\&F .
.
.Pp
\*(OPally \*(UA can send mail over SMTP network connections to a single
defined SMTP smart host by specifying a SMTP URL as the value (see
.Sx "On URL syntax and credential lookup" ) .
Note that with some mail providers it may be necessary to set the
.Va smtp-hostname
variable in order to use a specific combination of
.Va from ,
.Va hostname
and
.Va mta .
\*(UA also supports forwarding of all network traffic over a specified
.Va socks-proxy .
The following SMTP variants may be used:
.
.Bl -bullet
.It
The plain SMTP protocol (RFC 5321) that normally lives on the
server port 25 and requires setting the
.Va smtp-use-starttls
variable to enter a SSL/TLS encrypted session state.
Assign a value like \*(IN
.Ql smtp://[user[:password]@]server[:port]
(\*(OU
.Ql smtp://server[:port] )
to choose this protocol.
.It
The so-called SMTPS which is supposed to live on server port 465
and is automatically SSL/TLS secured.
Unfortunately it never became a standardized protocol and may thus not
be supported by your hosts network service database
\(en in fact the port number has already been reassigned to other
protocols!
.Pp
SMTPS is nonetheless a commonly offered protocol and thus can be
chosen by assigning a value like \*(IN
.Ql smtps://[user[:password]@]server[:port]
(\*(OU
.Ql smtps://server[:port] ) ;
due to the mentioned problems it is usually necessary to explicitly
specify the port as
.Ql :465 ,
however.
.It
Finally there is the SUBMISSION protocol (RFC 6409), which usually
lives on server port 587 and is practically identically to the SMTP
protocol from \*(UA's point of view beside that; it requires setting the
.Va smtp-use-starttls
variable to enter a SSL/TLS secured session state.
Assign a value like \*(IN
.Ql submission://[user[:password]@]server[:port]
(\*(OU
.Ql submission://server[:port] ) .
.El
.
.
.Mx
.It Va mta-arguments
Arguments to pass through to a file-based
.Va mta
can be given via this variable, which is parsed according to
.Sx "Shell-style argument quoting"
into an array of arguments, and which will be joined onto MTA options
from other sources, and then passed individually to the MTA:
.Ql ? wysh set mta-arguments='-t -X \&"/tmp/my log\&"' .
.
.Mx
.It Va mta-no-default-arguments
\*(BO Unless this variable is set \*(UA will pass some well known
standard command line options to a file-based
.Va mta
(Mail-Transfer-Agent), see there for more.
.
.Mx
.It Va mta-argv0
Many systems use a so-called
.Xr mailwrapper 8
environment to ensure compatibility with
.Xr sendmail 1 .
This works by inspecting the name that was used to invoke the mail
delivery system.
If this variable is set then the mailwrapper (the program that is
actually executed when calling the file-based
.Va mta )
will treat its contents as that name.
.
.Mx Va netrc-lookup
.It Va netrc-lookup-USER@HOST , netrc-lookup-HOST , netrc-lookup
\*(BO\*(IN\*(OP Used to control usage of the users
.Pa .netrc
file for lookup of account credentials, as documented in the section
.Sx "On URL syntax and credential lookup"
and for the command
.Ic netrc ;
the section
.Sx "The .netrc file"
documents the file format.
Also see
.Va netrc-pipe .
.
.Mx
.It Va netrc-pipe
\*(IN\*(OP When
.Pa .netrc
is loaded (see
.Ic netrc
and
.Va netrc-lookup )
then \*(UA will read the output of a shell pipe instead of the users
.Pa .netrc
file if this variable is set (to the desired shell command).
This can be used to, e.g., store
.Pa .netrc
in encrypted form:
.Ql ? set netrc-pipe='gpg -qd ~/.netrc.pgp' .
.
.Mx
.It Va newfolders
If this variable has the value
.Ql maildir ,
newly created local folders will be in Maildir instead of MBOX format.
.
.Mx
.It Va newmail
Checks for new mail in the current folder each time the prompt is shown.
A Maildir folder must be re-scanned to determine if new mail has arrived.
If this variable is set to the special value
.Ql nopoll
then a Maildir folder will not be rescanned completely, but only
timestamp changes are detected.
.
.Mx
.It Va outfolder
\*(BO Causes the filename given in the
.Va record
variable
and the sender-based filenames for the
.Ic Copy
and
.Ic Save
commands to be interpreted relative to the directory given in the
.Va folder
variable rather than to the current directory,
unless it is set to an absolute pathname.
.
.Mx
.It Va on-compose-cleanup
Macro hook which will be called after the message has been sent (or not,
in case of failures), as the very last step before unrolling compose mode
.Ic localopts .
This hook is run even in case of fatal errors, and it is advisable to
perform only absolutely necessary actions, like cleaning up
.Ic alternates ,
for example.
For compose mode hooks that may affect the message content please see
.Va on-compose-enter , on-compose-leave , on-compose-splice .
\*(ID This hook exists only because
.Ic alias , alternates , commandalias , shortcut ,
to name a few, are currently not covered by
.Ic localopts
or a similar mechanism: any changes applied in compose mode will
continue to be in effect thereafter.
.
.Mx
.Mx
.It Va on-compose-enter , on-compose-leave
Macro hooks which will be called before compose mode is entered,
and after composing has been finished (but before the
.Va signature
is injected, etc.), respectively.
.Ic localopts
are enabled for these hooks, causing any setting to be forgotten after
the message has been sent;
.Va on-compose-cleanup
can be used to perform any other necessary cleanup.
The following (read-only) variables will be set temporarily during
execution of the macros to represent the according message headers, or
the empty string for non-existent; they correspond to accoding virtual
temporary message headers that can be accessed via
.Ic ~^ ,
one of the
.Sx "COMMAND ESCAPES" :
.Pp
.Bl -tag -compact -width ".It Va mailx_subject"
.It Va mailx-command
The command that generates the message.
.It Va mailx-subject
The subject.
.It Va mailx-from
.Va from .
.It Va mailx-sender
.Va sender .
.It Va mailx-to , mailx-cc , mailx-bcc
The list of receiver addresses as a space-separated list.
.It Va mailx-raw-to , mailx-raw-cc , mailx-raw-bcc
The list of receiver addresses before any mangling (due to, e.g.,
.Ic alternates ,
.Ic alias
.Va recipients-in-cc )
as a space-separated list.
.It Va mailx-orig-from
When replying, forwarding or resending, this will be set to the
.Ql From:
of the given message.
.It Va mailx-orig-to , mailx-orig-cc , mailx-orig-bcc
When replying, forwarding or resending, this will be set to the
receivers of the given message.
.El
.
.
.Mx
.Mx
.It Va on-compose-splice , on-compose-splice-shell
These hooks run once the normal compose mode is finished, but before the
.Va on-compose-leave
macro hook is called, the
.Va signature
is injected etc.
Both hooks will be executed in a subprocess, with their input and output
connected to \*(UA such that they can act as if they would be an
interactive user.
The difference in between them is that the latter is a
.Ev SHELL
command, whereas the former is a normal \*(UA macro, but which is
restricted to a small set of commands (the
.Va verbose
output of, e.g.,
.Ic list
will indicate said capability).
.Ic localopts
are enabled for these hooks (in the parent process), causing any setting
to be forgotten after the message has been sent;
.Va on-compose-cleanup
can be used to perform other cleanup as necessary.
.
.Pp
During execution of these hooks \*(UA will temporarily forget whether it
has been started in interactive mode, (a restricted set of)
.Sx "COMMAND ESCAPES"
will always be available, and for guaranteed reproducibilities sake
.Va escape
and
.Va ifs
will be set to their defaults.
The compose mode command
.Ic ~^
has been especially designed for scriptability (via these hooks).
The first line the hook will read on its standard input is the protocol
version of said command escape, currently
.Dq 0 0 1 :
backward incompatible protocol changes have to be expected.
.
.Pp
Care must be taken to avoid deadlocks and other false control flow:
if both involved processes wait for more input to happen at the
same time, or one does not expect more input but the other is stuck
waiting for consumption of its output, etc.
There is no automatic synchronization of the hook: it will not be
stopped automatically just because it, e.g., emits
.Ql ~x .
The hooks will however receive a termination signal if the parent enters
an error condition.
\*(ID Protection against and interaction with signals is not yet given;
it is likely that in the future these scripts will be placed in an
isolated session, which is signalled in its entirety as necessary.
.
.Bd -literal -offset indent
wysh set on-compose-splice-shell=$'\e
  read version;\e
  printf "hello $version!  Headers: ";\e
  echo \e'~^header list\e';\e
  read status result;\e
  echo "status=$status result=$result";\e
  '

set on-compose-splice=ocsm
define ocsm {
  read ver
  echo Splice protocol version is $ver
  echo '~^h l'; read hl; vput vexpr es substring "${hl}" 0 1
  if [ "$es" != 2 ]
    echoerr 'Cannot read header list'; echo '~x'; xit
  endif
  if [ "$hl" @i!% ' cc' ]
    echo '~^h i cc Diet is your <mirr.or>'; read es;\e
      vput vexpr es substring "${es}" 0 1
    if [ "$es" != 2 ]
      echoerr 'Cannot insert Cc: header'; echo '~x'
    endif
  endif
}
.Ed
.
.
.Mx
.It Va on-resend-cleanup
\*(ID Identical to
.Va on-compose-cleanup ,
but is only triggered by
.Ic resend .
.
.Mx
.It Va on-resend-enter
\*(ID Identical to
.Va on-compose-enter ,
but is only triggered by
.Ic resend .
.
.Mx
.It Va page
\*(BO If set, each message feed through the command given for
.Ic pipe
is followed by a formfeed character
.Ql \ef .
.
.Mx Va password
.It Va password-USER@HOST , password-HOST , password
\*(IN Variable chain that sets a password, which is used in case none has
been given in the protocol and account-specific URL;
as a last resort \*(UA will ask for a password on the user's terminal if
the authentication method requires a password.
Specifying passwords in a startup file is generally a security risk;
the file should be readable by the invoking user only.
.
.It Va password-USER@HOST
\*(OU (see the chain above for \*(IN)
Set the password for
.Ql USER
when connecting to
.Ql HOST .
If no such variable is defined for a host,
the user will be asked for a password on standard input.
Specifying passwords in a startup file is generally a security risk;
the file should be readable by the invoking user only.
.
.Mx
.It Va piperaw
\*(BO Send messages to the
.Ic pipe
command without performing MIME and character set conversions.
.
.
.Mx
.It Va pipe-TYPE/SUBTYPE
When a MIME message part of type
.Ql TYPE/SUBTYPE
(case-insensitive) is displayed or quoted,
its text is filtered through the value of this variable interpreted as
a shell command.
Note that only parts which can be displayed inline as plain text (see
.Cd copiousoutput )
are displayed unless otherwise noted, other MIME parts will only be
considered by and for the command
.Ic mimeview .
.
.Pp
The special value commercial at
.Ql @
forces interpretation of the message part as plain text, e.g.,
.Ql set pipe-application/xml=@
will henceforth display XML
.Dq as is .
(The same could also be achieved by adding a MIME type marker with the
.Ic mimetype
command.
And \*(OPally MIME type handlers may be defined via
.Sx "The Mailcap files"
\(em these directives,
.Cd copiousoutput
has already been used, should be referred to for further documentation.
.
.Pp
The commercial at
.Ql @
can in fact be used as a trigger character to adjust usage and behaviour
of a following shell command specification more thoroughly by appending
more special characters which refer to further mailcap directives, e.g.,
the following hypothetical command specification could be used:
.
.Bd -literal -offset indent
? set pipe-X/Y='@!++=@vim ${MAILX_FILENAME_TEMPORARY}'
.Ed
.
.Pp
.Bl -tag -compact -width ".It Ql __"
.It Ql *
The command produces plain text to be integrated in \*(UAs output:
.Cd copiousoutput .
.
.It Ql #
If set the handler will not be invoked when a message is to be quoted,
but only when it will be displayed:
.Cd x-mailx-noquote .
.
.It Ql &
Run the command asynchronously, i.e., without blocking \*(UA:
.Cd x-mailx-async .
.
.It Ql \&!
The command must be run on an interactive terminal, \*(UA will
temporarily release the terminal to it:
.Cd needsterminal .
.
.It Ql +
Request creation of a zero-sized temporary file, the absolute pathname
of which will be made accessible via the environment variable
.Ev MAILX_FILENAME_TEMPORARY :
.Cd x-mailx-tmpfile .
If given twice then the file will be unlinked automatically by \*(UA
when the command loop is entered again at latest:
.Cd x-mailx-tmpfile-unlink .
.
.It Ql =
Normally the MIME part content is passed to the handler via standard
input; if this flag is set then the data will instead be written into
.Ev MAILX_FILENAME_TEMPORARY
.Pf ( Cd x-mailx-tmpfile-fill ) ,
the creation of which is implied; note however that in order to cause
deletion of the temporary file you still have to use two plus signs
.Ql ++
explicitly!
.
.It Ql @
To avoid ambiguities with normal shell command content you can use
another commercial at to forcefully terminate interpretation of
remaining characters.
(Any character not in this list will have the same effect.)
.El
.
.Pp
Some information about the MIME part to be displayed is embedded into
the environment of the shell command:
.
.Pp
.Bl -tag -compact -width ".It Ev _AIL__ILENAME__ENERATED"
.Mx
.It Ev MAILX_CONTENT
The MIME content-type of the part, if known, the empty string otherwise.
.
.Mx
.It Ev MAILX_CONTENT_EVIDENCE
If
.Va mime-counter-evidence
includes the carry-around-bit (2), then this will be set to the detected
MIME content-type; not only then identical to
.Ev \&\&MAILX_CONTENT
otherwise.
.
.Mx
.It Ev MAILX_FILENAME
The filename, if any is set, the empty string otherwise.
.
.Mx
.It Ev MAILX_FILENAME_GENERATED
A random string.
.
.Mx
.It Ev MAILX_FILENAME_TEMPORARY
If temporary file creation has been requested through the command prefix
this variable will be set and contain the absolute pathname of the
temporary file.
.El
.
.
.Mx
.It Va pipe-EXTENSION
This is identical to
.Va pipe-TYPE/SUBTYPE
except that
.Ql EXTENSION
(normalized to lowercase using character mappings of the ASCII charset)
names a file extension, e.g.,
.Ql xhtml .
Handlers registered using this method take precedence.
.
.Mx Va pop3-auth
.It Va pop3-auth-USER@HOST , pop3-auth-HOST , pop3-auth
\*(OP\*(IN Variable chain that sets the POP3 authentication method.
The only possible value as of now is
.Ql plain ,
which is thus the default.
.
.Mx
.Mx Va pop3-bulk-load
.It Va pop3-bulk-load-USER@HOST , pop3-bulk-load-HOST , pop3-bulk-load
\*(BO\*(OP When accessing a POP3 server \*(UA loads the headers of
the messages, and only requests the message bodies on user request.
For the POP3 protocol this means that the message headers will be
downloaded twice.
If this variable is set then \*(UA will download only complete messages
from the given POP3 server(s) instead.
.
.Mx Va pop3-keepalive
.It Va pop3-keepalive-USER@HOST , pop3-keepalive-HOST , pop3-keepalive
\*(OP POP3 servers close the connection after a period of inactivity;
the standard requires this to be at least 10 minutes,
but practical experience may vary.
Setting this variable to a numeric value greater than
.Ql 0
causes a
.Ql NOOP
command to be sent each value seconds if no other operation is performed.
.
.Mx Va pop3-no-apop
.It Va pop3-no-apop-USER@HOST , pop3-no-apop-HOST , pop3-no-apop
\*(BO\*(OP Unless this variable is set the
.Ql APOP
authentication method will be used when connecting to a POP3 server that
advertises support.
The advantage of
.Ql APOP
is that the password is not sent in clear text over the wire and that
only a single packet is sent for the user/password tuple.
Note that
.Va pop3-no-apop-HOST
requires \*(IN.
.
.Mx Va pop3-use-starttls
.It Va pop3-use-starttls-USER@HOST , pop3-use-starttls-HOST , pop3-use-starttls
\*(BO\*(OP Causes \*(UA to issue a
.Ql STLS
command to make an unencrypted POP3 session SSL/TLS encrypted.
This functionality is not supported by all servers,
and is not used if the session is already encrypted by the POP3S method.
Note that
.Va pop3-use-starttls-HOST
requires \*(IN.
.
.
.Mx
.It Va posix
\*(BO This flag enables POSIX mode, which changes behaviour of \*(UA
where that deviates from standardized behaviour.
It will be set implicitly before the
.Sx "Resource files"
are loaded if the environment variable
.Ev POSIXLY_CORRECT
is set, and adjusting any of those two will be reflected by the other
one implicitly.
The following behaviour is covered and enforced by this mechanism:
.
.Pp
.Bl -bullet -compact
.It
In non-interactive mode, any error encountered while loading resource
files during program startup will cause a program exit, whereas in
interactive mode such errors will stop loading of the currently loaded
(stack of) file(s, i.e., recursively).
These exits can be circumvented on a per-command base by using
.Cm ignerr ,
one of the
.Sx "Command modifiers" ,
for each command which shall be allowed to fail.
.
.It
.Ic alternates
will replace the list of alternate addresses instead of appending to it.
.
.It
Upon changing the active
.Ic file
no summary of
.Ic headers
will be displayed even if
.Va header
is set.
.
.It
Setting
.Va ignoreeof
implies the behaviour described by
.Va dot .
.
.It
The variable
.Va keep
is extended to cover any empty mailbox, not only empty
.Mx -sx
.Sx "primary system mailbox" Ns
es: they will be removed when they are left in empty state otherwise.
.El
.
.
.Mx
.It Va print-alternatives
\*(BO When a MIME message part of type
.Ql multipart/alternative
is displayed and it contains a subpart of type
.Ql text/plain ,
other parts are normally discarded.
Setting this variable causes all subparts to be displayed,
just as if the surrounding part was of type
.Ql multipart/mixed .
.
.Mx
.It Va prompt
The string used as a prompt in interactive mode.
Whenever the variable is evaluated the value is expanded as via
dollar-single-quote expansion (see
.Sx "Shell-style argument quoting" ) .
This (post-assignment, i.e., second) expansion can be used to embed
status information, for example
.Va \&? ,
.Va \&! ,
.Va account
or
.Va mailbox-display .
.Pp
In order to embed characters which should not be counted when
calculating the visual width of the resulting string, enclose the
characters of interest in a pair of reverse solidus escaped brackets:
.Ql \e[\eE[0m\e] ;
a slot for coloured prompts is also available with the \*(OPal command
.Ic colour .
Prompting may be prevented by setting this to the null string
(a.k.a.\|
.Ql set noprompt ) .
.
.Mx
.It Va prompt2
This string is used for secondary prompts, but is otherwise identical to
.Va prompt .
The default is
.Ql ..\0 .
.
.Mx
.It Va quiet
\*(BO Suppresses the printing of the version when first invoked.
.
.Mx
.It Va quote
If set, \*(UA starts a replying message with the original message
prefixed by the value of the variable
.Va indentprefix .
Normally, a heading consisting of
.Dq Fromheaderfield wrote:
is put before the quotation.
If the string
.Ql noheading
is assigned to the
.Va \&\&quote
variable, this heading is omitted.
If the string
.Ql headers
is assigned, only the headers selected by the
.Ql type
.Ic headerpick
selection are put above the message body,
thus
.Va \&\&quote
acts like an automatic
.Pf ` Ic ~m Ns '
.Sx "COMMAND ESCAPES"
command, then.
If the string
.Ql allheaders
is assigned, all headers are put above the message body and all MIME
parts are included, making
.Va \&\&quote
act like an automatic
.Pf ` Ic ~M Ns '
command; also see
.Va quote-as-attachment .
.
.Mx
.It Va quote-as-attachment
\*(BO Add the original message in its entirety as a
.Ql message/rfc822
MIME attachment when replying to a message.
Note this works regardless of the setting of
.Va quote .
.
.Mx
.It Va quote-fold
\*(OP Can be set in addition to
.Va indentprefix .
Setting this turns on a more fancy quotation algorithm in that leading
quotation characters are compressed and overlong lines are folded.
.Va \&\&quote-fold
can be set to either one or two (space separated) numeric values,
which are interpreted as the maximum (goal) and the minimum line length,
respectively, in a spirit rather equal to the
.Xr fmt 1
program, but line-, not paragraph-based.
If not set explicitly the minimum will reflect the goal algorithmically.
The goal cannot be smaller than the length of
.Va indentprefix
plus some additional pad.
Necessary adjustments take place silently.
.
.Mx
.It Va r-option-implicit
\*(BO Setting this option evaluates the contents of
.Va from
(or, if that contains multiple addresses,
.Va sender )
and passes the results onto the used (file-based) MTA as described for the
.Fl r
option (empty argument case).
.
.Mx
.It Va recipients-in-cc
\*(BO When doing a
.Ic reply ,
the original
.Ql From:
and
.Ql To:
are by default merged into the new
.Ql To: .
If this variable is set, only the original
.Ql From:
ends in the new
.Ql To: ,
the rest is merged into
.Ql Cc: .
.
.Mx
.It Va record
Unless this variable is defined, no copies of outgoing mail will be saved.
If defined it gives the pathname, subject to the usual
.Sx "Filename transformations" ,
of a folder where all new, replied-to or forwarded messages are saved:
when saving to this folder fails the message is not sent, but instead
.Va save Ns
d to
.Ev DEAD .
The standard defines that relative (fully expanded) paths are to be
interpreted relative to the current directory
.Pf ( Ic cwd ) ,
to force interpretation relative to
.Va folder
.Va outfolder
needs to be set in addition.
.
.Mx
.It Va record-files
\*(BO If this variable is set the meaning of
.Va record
will be extended to cover messages which target only file and pipe
recipients (see
.Va expandaddr ) .
These address types will not appear in recipient lists unless
.Va add-file-recipients
is also set.
.
.Mx
.It Va record-resent
\*(BO If this variable is set the meaning of
.Va record
will be extended to also cover the
.Ic resend
and
.Ic Resend
commands.
.
.Mx
.It Va reply-in-same-charset
\*(BO If this variable is set \*(UA first tries to use the same
character set of the original message for replies.
If this fails, the mechanism described in
.Sx "Character sets"
is evaluated as usual.
.
.Mx
.It Va reply-strings
Can be set to a comma-separated list of (case-insensitive according to
ASCII rules) strings which shall be recognized in addition to the
built-in strings as
.Ql Subject:
reply message indicators \(en built-in are
.Ql Re: ,
which is mandated by RFC 5322, as well as the german
.Ql Aw: ,
.Ql Antw: ,
and the
.Ql Wg:
which often has been seen in the wild;
I.e., the separating colon has to be specified explicitly.
.
.Mx
.It Va replyto
A list of addresses to put into the
.Ql Reply-To:
field of the message header.
Members of this list are handled as if they were in the
.Ic alternates
list.
.
.Mx
.It Va reply-to-honour
Controls whether a
.Ql Reply-To:
header is honoured when replying to a message via
.Ic reply
or
.Ic Lreply .
This is a quadoption; if set without a value it defaults to
.Dq yes .
.
.Mx
.It Va rfc822-body-from_
\*(BO This variable can be used to force displaying a so-called
.Ql From_
line for messages that are embedded into an envelope mail via the
.Ql message/rfc822
MIME mechanism, for more visual convenience.
.
.Mx
.It Va save
\*(BO Enable saving of (partial) messages in
.Ev DEAD
upon interrupt or delivery error.
.
.Mx
.It Va screen
The number of lines that represents a
.Dq screenful
of lines, used in
.Ic headers
summary display,
.Ic from
.Ic search Ns
ing, message
.Ic top Ns
line display and scrolling via
.Ic z .
If this variable is not set \*(UA falls back to a calculation based upon
the detected terminal window size and the baud rate: the faster the
terminal, the more will be shown.
Overall screen dimensions and pager usage is influenced by the
environment variables
.Ev COLUMNS
and
.Ev LINES
and the variable
.Va crt .
.
.Mx
.It Va searchheaders
\*(BO Expand message-list specifiers in the form
.Ql /x:y
to all messages containing the substring
.Dq y
in the header field
.Ql x .
The string search is case insensitive.
.
.Mx
.It Va sendcharsets
\*(OP A comma-separated list of character set names that can be used in
outgoing internet mail.
The value of the variable
.Va charset-8bit
is automatically appended to this list of character sets.
If no character set conversion capabilities are compiled into \*(UA then
the only supported charset is
.Va ttycharset .
Also see
.Va sendcharsets-else-ttycharset
and refer to the section
.Sx "Character sets"
for the complete picture of character set conversion in \*(UA.
.
.Mx
.It Va sendcharsets-else-ttycharset
\*(BO\*(OP If this variable is set, but
.Va sendcharsets
is not, then \*(UA acts as if
.Va sendcharsets
had been set to the value of the variable
.Va ttycharset .
In effect this combination passes through the message data in the
character set of the current locale encoding:
therefore mail message text will be (assumed to be) in ISO-8859-1
encoding when send from within a ISO-8859-1 locale, and in UTF-8
encoding when send from within an UTF-8 locale.
.Pp
The 8-bit fallback
.Va charset-8bit
never comes into play as
.Va ttycharset
is implicitly assumed to be 8-bit and capable to represent all files the
user may specify (as is the case when no character set conversion
support is available in \*(UA and the only supported character set is
.Va ttycharset :
.Sx "Character sets" ) .
This might be a problem for scripts which use the suggested
.Ql LC_ALL=C
setting, since in this case the character set is US-ASCII by definition,
so that it is better to also override
.Va ttycharset ,
then.
.
.Mx
.It Va sender
An address that is put into the
.Ql Sender:
field of outgoing messages, quoting RFC 5322: the mailbox of the agent
responsible for the actual transmission of the message.
This field should normally not be used unless the
.Va from
field contains more than one address, on which case it is required.
The
.Va \&\&sender
address is handled as if it were in the
.Ic alternates
list; also see
.Fl r ,
.Va r-option-implicit .
.
.It Va sendmail
\*(OB Predecessor of
.Va mta .
.
.It Va sendmail-arguments
\*(OB Predecessor of
.Va mta-arguments .
.
.It Va sendmail-no-default-arguments
\*(OB\*(BO Predecessor of
.Va mta-no-default-arguments .
.
.It Va sendmail-progname
\*(OB Predecessor of
.Va mta-argv0 .
.
.Mx
.It Va sendwait
\*(BO When sending a message wait until the
.Va mta
(including the built-in SMTP one) exits before accepting further commands.
.Sy Only
with this variable set errors reported by the MTA will be recognizable!
If the MTA returns a non-zero exit status,
the exit status of \*(UA will also be non-zero.
.
.Mx
.It Va showlast
\*(BO This setting causes \*(UA to start at the last message
instead of the first one when opening a mail folder.
.
.Mx
.It Va showname
\*(BO Causes \*(UA to use the sender's real name instead of the plain
address in the header field summary and in message specifications.
.
.Mx
.It Va showto
\*(BO Causes the recipient of the message to be shown in the header
summary if the message was sent by the user.
.
.Mx
.It Va Sign
The string to expand
.Ic ~A
to (see
.Sx "COMMAND ESCAPES" ) .
.
.Mx
.It Va sign
The string to expand
.Ic ~a
to (see
.Sx "COMMAND ESCAPES" ) .
.
.Mx
.It Va signature
Must correspond to the name of a readable file if set.
The file's content is then appended to each singlepart message
and to the first part of each multipart message.
Be warned that there is no possibility to edit the signature for an
individual message.
.
.Mx
.It Va skipemptybody
\*(BO If an outgoing message does not contain any text in its first or
only message part, do not send it but discard it silently (see also the
command line option
.Fl E ) .
.
.Mx
.Mx
.It Va smime-ca-dir , smime-ca-file
\*(OP Specify the location of trusted CA certificates in PEM (Privacy
Enhanced Mail) format as a directory and a file, respectively, for the
purpose of verification of S/MIME signed messages.
It is possible to set both, the file will be loaded immediately, the
directory will be searched whenever no match has yet been found.
The set of CA certificates which are built into the SSL/TLS library can
be explicitly turned off by setting
.Va smime-ca-no-defaults ,
and further fine-tuning is possible via
.Va smime-ca-flags .
.
.Mx
.It Va smime-ca-flags
\*(OP Can be used to fine-tune behaviour of the X509 CA certificate
storage, and the certificate verification that is used.
The actual values and their meanings are documented for
.Va ssl-ca-flags .
.
.Mx
.It Va smime-ca-no-defaults
\*(BO\*(OP Do not load the default CA locations that are built into the
used to SSL/TLS library to verify S/MIME signed messages.
.
.Mx Va smime-cipher
.It Va smime-cipher-USER@HOST , smime-cipher
\*(OP Specifies the cipher to use when generating S/MIME encrypted
messages (for the specified account).
RFC 5751 mandates a default of
.Ql aes128
(AES-128 CBC).
Possible values are (case-insensitive and) in decreasing cipher strength:
.Ql aes256
(AES-256 CBC),
.Ql aes192
(AES-192 CBC),
.Ql aes128
(AES-128 CBC),
.Ql des3
(DES EDE3 CBC, 168 bits; default if
.Ql aes128
is not available) and
.Ql des
(DES CBC, 56 bits).
.Pp
The actually available cipher algorithms depend on the cryptographic
library that \*(UA uses.
\*(OP Support for more cipher algorithms may be available through
dynamic loading via, e.g.,
.Xr EVP_get_cipherbyname 3
(OpenSSL) if \*(UA has been compiled to support this.
.
.Mx
.It Va smime-crl-dir
\*(OP Specifies a directory that contains files with CRLs in PEM format
to use when verifying S/MIME messages.
.
.Mx
.It Va smime-crl-file
\*(OP Specifies a file that contains a CRL in PEM format to use when
verifying S/MIME messages.
.
.Mx
.It Va smime-encrypt-USER@HOST
\*(OP If this variable is set, messages send to the given receiver are
encrypted before sending.
The value of the variable must be set to the name of a file that
contains a certificate in PEM format.
.Pp
If a message is sent to multiple recipients,
each of them for whom a corresponding variable is set will receive an
individually encrypted message;
other recipients will continue to receive the message in plain text
unless the
.Va smime-force-encryption
variable is set.
It is recommended to sign encrypted messages, i.e., to also set the
.Va smime-sign
variable.
.
.Mx
.It Va smime-force-encryption
\*(BO\*(OP Causes \*(UA to refuse sending unencrypted messages.
.
.Mx
.It Va smime-sign
\*(BO\*(OP S/MIME sign outgoing messages with the user's private key
and include the user's certificate as a MIME attachment.
Signing a message enables a recipient to verify that the sender used
a valid certificate,
that the email addresses in the certificate match those in the message
header and that the message content has not been altered.
It does not change the message text,
and people will be able to read the message as usual.
Also see
.Va smime-sign-cert , smime-sign-include-certs
and
.Va smime-sign-message-digest .
.
.Mx Va smime-sign-cert
.It Va smime-sign-cert-USER@HOST , smime-sign-cert
\*(OP Points to a file in PEM format.
For the purpose of signing and decryption this file needs to contain the
user's private key, followed by his certificate.
.Pp
For message signing
.Ql USER@HOST
is always derived from the value of
.Va from
(or, if that contains multiple addresses,
.Va sender ) .
For the purpose of encryption the recipient's public encryption key
(certificate) is expected; the command
.Ic certsave
can be used to save certificates of signed messages (the section
.Sx "Signed and encrypted messages with S/MIME"
gives some details).
This mode of operation is usually driven by the specialized form.
.Pp
When decrypting messages the account is derived from the recipient
fields
.Pf ( Ql To:
and
.Ql Cc: )
of the message, which are searched for addresses for which such
a variable is set.
\*(UA always uses the first address that matches,
so if the same message is sent to more than one of the user's addresses
using different encryption keys, decryption might fail.
.Pp
For signing and decryption purposes it is possible to use encrypted
keys, and the pseudo-host(s)
.Ql USER@HOST.smime-cert-key
for the private key
(and
.Ql USER@HOST.smime-cert-cert
for the certificate stored in the same file)
will be used for performing any necessary password lookup,
therefore the lookup can be automatized via the mechanisms described in
.Sx "On URL syntax and credential lookup" .
For example, the hypothetical address
.Ql bob@exam.ple
could be driven with a private key / certificate pair path defined in
.Va \&\&smime-sign-cert-bob@exam.ple ,
and needed passwords would then be looked up via the pseudo hosts
.Ql bob@exam.ple.smime-cert-key
(and
.Ql bob@exam.ple.smime-cert-cert ) .
To include intermediate certificates, use
.Va smime-sign-include-certs .
.
.Mx Va smime-sign-include-certs
.It Va smime-sign-include-certs-USER@HOST , smime-sign-include-certs
\*(OP If used, this is supposed to a consist of a comma-separated list
of files, each of which containing a single certificate in PEM format to
be included in the S/MIME message in addition to the
.Va smime-sign-cert
certificate.
This can be used to include intermediate certificates of the certificate
authority, in order to allow the receiver's S/MIME implementation to
perform a verification of the entire certificate chain, starting from
a local root certificate, over the intermediate certificates, down to the
.Va smime-sign-cert .
Even though top level certificates may also be included in the chain,
they won't be used for the verification on the receiver's side.
.Pp
For the purpose of the mechanisms involved here,
.Ql USER@HOST
refers to the content of the internal variable
.Va from
(or, if that contains multiple addresses,
.Va sender ) .
The pseudo-host
.Ql USER@HOST.smime-include-certs
will be used for performing password lookups for these certificates,
shall they have been given one, therefore the lookup can be automatized
via the mechanisms described in
.Sx "On URL syntax and credential lookup" .
.
.Mx Va smime-sign-message-digest
.It Va smime-sign-message-digest-USER@HOST , smime-sign-message-digest
\*(OP Specifies the message digest to use when signing S/MIME messages.
RFC 5751 mandates a default of
.Ql sha1 .
Possible values are (case-insensitive and) in decreasing cipher strength:
.Ql sha512 ,
.Ql sha384 ,
.Ql sha256 ,
.Ql sha224
and
.Ql md5 .
.Pp
The actually available message digest algorithms depend on the
cryptographic library that \*(UA uses.
\*(OP Support for more message digest algorithms may be available
through dynamic loading via, e.g.,
.Xr EVP_get_digestbyname 3
(OpenSSL) if \*(UA has been compiled to support this.
Remember that for this
.Ql USER@HOST
refers to the variable
.Va from
(or, if that contains multiple addresses,
.Va sender ) .
.
.It Va smtp
\*(OB\*(OP To use the built-in SMTP transport, specify a SMTP URL in
.Va mta .
\*(ID For compatibility reasons a set
.Va smtp
is used in preference of
.Va mta .
.
.Mx Va smtp-auth
.It Va smtp-auth-USER@HOST , smtp-auth-HOST , smtp-auth
\*(OP Variable chain that controls the SMTP
.Va mta
authentication method, possible values are
.Ql none
(\*(OU default),
.Ql plain
(\*(IN default),
.Ql login
as well as the \*(OPal methods
.Ql cram-md5
and
.Ql gssapi .
The
.Ql none
method does not need any user credentials,
.Ql gssapi
requires a user name and all other methods require a user name and
a password.
See \*(IN
.Va mta ,
.Va user
and
.Va password
(\*(OU
.Va smtp-auth-password
and
.Va smtp-auth-user ) .
Note that
.Va smtp-auth-HOST
is \*(IN.
\*(OU: Note for
.Va smtp-auth-USER@HOST :
may override dependent on sender address in the variable
.Va from .
.
.It Va smtp-auth-password
\*(OP\*(OU Sets the global fallback password for SMTP authentication.
If the authentication method requires a password, but neither
.Va smtp-auth-password
nor a matching
.Va smtp-auth-password-USER@HOST
can be found,
\*(UA will ask for a password on the user's terminal.
.
.It Va smtp-auth-password-USER@HOST
\*(OU Overrides
.Va smtp-auth-password
for specific values of sender addresses, dependent upon the variable
.Va from .
.
.It Va smtp-auth-user
\*(OP\*(OU Sets the global fallback user name for SMTP authentication.
If the authentication method requires a user name, but neither
.Va smtp-auth-user
nor a matching
.Va smtp-auth-user-USER@HOST
can be found,
\*(UA will ask for a user name on the user's terminal.
.
.It Va smtp-auth-user-USER@HOST
\*(OU Overrides
.Va smtp-auth-user
for specific values of sender addresses, dependent upon the variable
.Va from .
.
.Mx
.It Va smtp-hostname
\*(OP\*(IN Normally \*(UA uses the variable
.Va from
to derive the necessary
.Ql USER@HOST
information in order to issue a
.Ql MAIL FROM:<>
SMTP
.Va mta
command.
Setting
.Va smtp-hostname
can be used to use the
.Ql USER
from the SMTP account
.Pf ( Va mta
or the
.Va user
variable chain)
and the
.Ql HOST
from the content of this variable (or, if that is the empty string,
.Va hostname
or the local hostname as a last resort).
This often allows using an address that is itself valid but hosted by
a provider other than which (in
.Va from )
is about to send the message.
Setting this variable also influences generated
.Ql Message-ID:
and
.Ql Content-ID:
header fields.
.
.Mx Va smtp-use-starttls
.It Va smtp-use-starttls-USER@HOST , smtp-use-starttls-HOST , smtp-use-starttls
\*(BO\*(OP Causes \*(UA to issue a
.Ql STARTTLS
command to make an SMTP
.Va mta
session SSL/TLS encrypted, i.e., to enable transport layer security.
.
.Mx Va socks-proxy
.It Va socks-proxy-USER@HOST , socks-proxy-HOST , socks-proxy
\*(OP If this is set to the hostname (SOCKS URL) of a SOCKS5 server then
\*(UA will proxy all of its network activities through it.
This can be used to proxy SMTP, POP3 etc. network traffic through the
Tor anonymizer, for example.
The following would create a local SOCKS proxy on port 10000 that
forwards to the machine
.Ql HOST ,
and from which the network traffic is actually instantiated:
.Bd -literal -offset indent
# Create local proxy server in terminal 1 forwarding to HOST
$ ssh -D 10000 USER@HOST
# Then, start a client that uses it in terminal 2
$ \*(uA -Ssocks-proxy-USER@HOST=localhost:10000
.Ed
.
.Mx
.It Va spam-interface
\*(OP In order to use any of the spam-related commands (like, e.g.,
.Ic spamrate )
the desired spam interface must be defined by setting this variable.
Please refer to the manual section
.Sx "Handling spam"
for the complete picture of spam handling in \*(UA.
All or none of the following interfaces may be available:
.
.Bl -tag -width ".It Ql _ilte_"
.It Ql spamc
Interaction with
.Xr spamc 1
from the
.Xr spamassassin 1
.Pf ( Lk http://spamassassin.apache.org SpamAssassin )
suite.
Different to the generic filter interface \*(UA will automatically add
the correct arguments for a given command and has the necessary
knowledge to parse the program's output.
A default value for
.Va spamc-command
will have been compiled into the \*(UA binary if
.Xr spamc 1
has been found in
.Ev PATH
during compilation.
Shall it be necessary to define a specific connection type (rather than
using a configuration file for that), the variable
.Va spamc-arguments
can be used as in, e.g.,
.Ql -d server.example.com -p 783 .
It is also possible to specify a per-user configuration via
.Va spamc-user .
Note that this interface does not inspect the
.Ql is-spam
flag of a message for the command
.Ic spamforget .
.
.It Ql filter
generic spam filter support via freely configurable hooks.
This interface is meant for programs like
.Xr bogofilter 1
and requires according behaviour in respect to the hooks' exit
status for at least the command
.Ic spamrate
.Pf ( Ql 0
meaning a message is spam,
.Ql 1
for non-spam,
.Ql 2
for unsure and any other return value indicating a hard error);
since the hooks can include shell code snippets diverting behaviour
can be intercepted as necessary.
The hooks are
.Va spamfilter-ham , spamfilter-noham , spamfilter-nospam , \
  spamfilter-rate
and
.Va spamfilter-spam ;
the manual section
.Sx "Handling spam"
contains examples for some programs.
The process environment of the hooks will have the variable
.Ev MAILX_FILENAME_GENERATED
set.
Note that spam score support for
.Ic spamrate
is not supported unless the \*(OPtional regular expression support is
available and the
.Va spamfilter-rate-scanscore
variable is set.
.El
.
.
.Mx
.It Va spam-maxsize
\*(OP Messages that exceed this size will not be passed through to the
configured
.Va spam-interface .
If unset or 0, the default of 420000 bytes is used.
.
.Mx
.It Va spamc-command
\*(OP The path to the
.Xr spamc 1
program for the
.Ql spamc
.Va spam-interface .
Note that the path is not expanded, but used
.Dq as is .
A fallback path will have been compiled into the \*(UA binary if the
executable had been found during compilation.
.
.Mx
.It Va spamc-arguments
\*(OP Even though \*(UA deals with most arguments for the
.Ql spamc
.Va spam-interface
automatically, it may at least sometimes be desirable to specify
connection-related ones via this variable, e.g.,
.Ql -d server.example.com -p 783 .
.
.Mx
.It Va spamc-user
\*(OP Specify a username for per-user configuration files for the
.Ql spamc
.Va spam-interface .
If this is set to the empty string then \*(UA will use the name of the
current
.Va user .
.
.Mx
.Mx
.Mx
.Mx
.Mx
.It Va spamfilter-ham , spamfilter-noham , \
  spamfilter-nospam , spamfilter-rate , spamfilter-spam
\*(OP Command and argument hooks for the
.Ql filter
.Va spam-interface .
The manual section
.Sx "Handling spam"
contains examples for some programs.
.
.Mx
.It Va spamfilter-rate-scanscore
\*(OP Because of the generic nature of the
.Ql filter
.Va spam-interface
spam scores are not supported for it by default, but if the \*(OPnal
regular expression support is available then setting this variable can
be used to overcome this restriction.
It is interpreted as follows: first a number (digits) is parsed that
must be followed by a semicolon
.Ql \&;
and an extended regular expression.
Then the latter is used to parse the first output line of the
.Va spamfilter-rate
hook, and, in case the evaluation is successful, the group that has been
specified via the number is interpreted as a floating point scan score.
.
.Mx
.Mx
.It Va ssl-ca-dir , ssl-ca-file
\*(OP Specify the location of trusted CA certificates in PEM (Privacy
Enhanced Mail) format as a directory and a file, respectively, for the
purpose of verification of SSL/TLS server certificates.
It is possible to set both, the file will be loaded immediately, the
directory will be searched whenever no match has yet been found.
The set of CA certificates which are built into the SSL/TLS library can
be explicitly turned off by setting
.Va ssl-ca-no-defaults ,
and further fine-tuning is possible via
.Va ssl-ca-flags ;
also see
.Xr SSL_CTX_load_verify_locations 3
for more information.
\*(UA will try to use the TLS/SNI (ServerNameIndication) extension when
establishing TLS connections to servers identified with hostnames.
.
.
.Mx
.It Va ssl-ca-flags
\*(OP Can be used to fine-tune behaviour of the X509 CA certificate
storage, and the certificate verification that is used (also see
.Va ssl-verify ) .
The value is expected to consist of a comma-separated list of
configuration directives, with any intervening whitespace being ignored.
The directives directly map to flags that can be passed to
.Xr X509_STORE_set_flags 3 ,
which are usually defined in a file
.Pa openssl/x509_vfy.h ,
and the availability of which depends on the used SSL/TLS library
version: a directive without mapping is ignored (error log subject to
.Va debug ) .
Directives currently understood (case-insensitively) include:
.
.Pp
.Bl -tag -compact -width ".It Cd BaNg"
.It Cd no-alt-chains
If the initial chain is not trusted, do not attempt to build an
alternative chain.
Setting this flag will make OpenSSL certificate verification match that
of older OpenSSL versions, before automatic building and checking of
alternative chains has been implemented; also see
.Cd trusted-first .
.It Cd no-check-time
Do not check certificate/CRL validity against current time.
.It Cd partial-chain
By default partial, incomplete chains which cannot be verified up to the
chain top, a self-signed root certificate, will not verify.
With this flag set, a chain succeeds to verify if at least one signing
certificate of the chain is in any of the configured trusted stores of
CA certificates.
The OpenSSL manual page
.Xr SSL_CTX_load_verify_locations 3
gives some advise how to manage your own trusted store of CA certificates.
.It Cd strict
Disable workarounds for broken certificates.
.It Cd trusted-first
Try building a chain using issuers in the trusted store first to avoid
problems with server-sent legacy intermediate certificates.
Newer versions of OpenSSL support alternative chain checking and enable
it by default, resulting in the same behaviour; also see
.Cd no-alt-chains .
.El
.
.
.Mx
.It Va ssl-ca-no-defaults
\*(BO\*(OP Do not load the default CA locations that are built into the
used to SSL/TLS library to verify SSL/TLS server certificates.
.
.Mx Va ssl-cert
.It Va ssl-cert-USER@HOST , ssl-cert-HOST , ssl-cert
\*(OP Variable chain that sets the filename for a SSL/TLS client
certificate required by some servers.
This is a direct interface to the
.Ql Certificate
slot of the
.Xr SSL_CONF_cmd 3
function of the OpenSSL library, if available.
.
.Mx Va ssl-cipher-list
.It Va ssl-cipher-list-USER@HOST , ssl-cipher-list-HOST , ssl-cipher-list
\*(OP Specifies a list of ciphers for SSL/TLS connections.
This is a direct interface to the
.Ql CipherString
slot of the
.Xr SSL_CONF_cmd 3
function of the OpenSSL library, if available; see
.Xr ciphers 1
and
.Xr SSL_CTX_set_cipher_list 3
for more information.
By default \*(UA does not set a list of ciphers, in effect using a
.Va ssl-protocol
specific cipher (protocol standards ship with a list of acceptable
ciphers), possibly cramped to what the actually used SSL/TLS library
supports \(en the manual section
.Sx "An example configuration"
also contains a SSL/TLS use case.
.
.Mx
.It Va ssl-config-file
\*(OP If this variable is set \*(UA will call
.Xr CONF_modules_load_file 3
to allow OpenSSL to be configured according to the host system wide
security settings.
If a non-empty value is given then this will be used to specify the
configuration file to be used instead of the global OpenSSL default;
note that in this case it is an error if the file cannot be loaded.
The application name will always be passed as
.Dq \*(uA .
.
.Mx Va ssl-curves
.It Va ssl-curves-USER@HOST , ssl-curves-HOST , ssl-curves
\*(OP Specifies a list of supported curves for SSL/TLS connections.
This is a direct interface to the
.Ql Curves
slot of the
.Xr SSL_CONF_cmd 3
function of the OpenSSL library, if available; see
.Xr SSL_CTX_set1_curves_list 3
for more information.
By default \*(UA does not set a list of curves.
.
.Mx
.Mx
.It Va ssl-crl-dir , ssl-crl-file
\*(OP Specify a directory / a file, respectively that contains a CRL in
PEM format to use when verifying SSL/TLS server certificates.
.
.Mx Va ssl-key
.It Va ssl-key-USER@HOST , ssl-key-HOST , ssl-key
\*(OP Variable chain that sets the filename for the private key of
a SSL/TLS client certificate.
If unset, the name of the certificate file is used.
The file is expected to be in PEM format.
This is a direct interface to the
.Ql PrivateKey
slot of the
.Xr SSL_CONF_cmd 3
function of the OpenSSL library, if available.
.
.It Va ssl-method-USER@HOST , ssl-method-HOST , ssl-method
\*(OB\*(OP Please use the newer and more flexible
.Va ssl-protocol
instead: if both values are set,
.Va ssl-protocol
will take precedence!
Can be set to the following values, the actually used
.Va ssl-protocol
specification to which it is mapped is shown in parenthesis:
.Ql tls1.2
.Pf ( Ql -ALL, TLSv1.2 ) ,
.Ql tls1.1
.Pf ( Ql -ALL, TLSv1.1 ) ,
.Ql tls1
.Pf ( Ql -ALL, TLSv1 )
and
.Ql ssl3
.Pf ( Ql -ALL, SSLv3 ) ;
the special value
.Ql auto
is mapped to
.Ql ALL, -SSLv2
and thus includes the SSLv3 protocol.
Note that SSLv2 is no longer supported at all.
.
.Mx Va ssl-protocol
.It Va ssl-protocol-USER@HOST , ssl-protocol-HOST , ssl-protocol
\*(OP Specify the used SSL/TLS protocol.
This is a direct interface to the
.Ql Protocol
slot of the
.Xr SSL_CONF_cmd 3
function of the OpenSSL library, if available;
otherwise an \*(UA internal parser is used which understands the
following subset of (case-insensitive) command strings:
.Ql SSLv3 ,
.Ql TLSv1 ,
.Ql TLSv1.1
and
.Ql TLSv1.2 ,
as well as the special value
.Ql ALL .
Multiple specifications may be given via a comma-separated list which
ignores any whitespace.
An optional
.Ql +
plus sign prefix will enable a protocol, a
.Ql -
hyphen-minus prefix will disable it, so that
.Ql -ALL, TLSv1.2
will enable only the TLSv1.2 protocol.
.Pp
It depends upon the used TLS/SSL library which protocols are actually
supported and which protocols are used if
.Va ssl-protocol
is not set, but note that SSLv2 is no longer supported at all and
actively disabled.
Especially for older protocols explicitly securing
.Va ssl-cipher-list
may be worthwile, see
.Sx "An example configuration" .
.
.Mx
.It Va ssl-rand-egd
\*(OP Gives the pathname to an entropy daemon socket, see
.Xr RAND_egd 3 .
Not all SSL/TLS libraries support this.
.
.Mx
.It Va ssl-rand-file
\*(OP Gives the filename to a file with random entropy data, see
.Xr RAND_load_file 3 .
If this variable is not set, or set to the empty string, or if the
.Sx "Filename transformations"
fail, then
.Xr RAND_file_name 3
will be used to create the filename if, and only if,
.Xr RAND_status 3
documents that the SSL PRNG is not yet sufficiently seeded.
If \*(UA successfully seeded the SSL PRNG then it will update the file
.Pf ( Xr RAND_write_file 3 ) .
This variable is only used if
.Va ssl-rand-egd
is not set (or not supported by the SSL/TLS library).
.
.Mx Va ssl-verify
.It Va ssl-verify-USER@HOST , ssl-verify-HOST , ssl-verify
\*(OP Variable chain that sets the action to be performed if an error
occurs during SSL/TLS server certificate validation against the
specified or default trust stores
.Va ssl-ca-dir ,
.Va ssl-ca-file ,
or the SSL/TLS library built-in defaults (unless usage disallowed via
.Va ssl-ca-no-defaults ) ,
and as fine-tuned via
.Va ssl-ca-flags .
Valid (case-insensitive) values are
.Ql strict
(fail and close connection immediately),
.Ql ask
(ask whether to continue on standard input),
.Ql warn
(show a warning and continue),
.Ql ignore
(do not perform validation).
The default is
.Ql ask .
.
.Mx
.It Va stealthmua
If only set without an assigned value, then this setting inhibits the
generation of the
.Ql Message-ID: ,
.Ql Content-ID:
and
.Ql User-Agent:
header fields that include obvious references to \*(UA.
There are two pitfalls associated with this:
First, the message id of outgoing messages is not known anymore.
Second, an expert may still use the remaining information in the header
to track down the originating mail user agent.
If set to the value
.Ql noagent ,
then the mentioned
.Ql Message-ID:
and
.Ql Content-ID:
suppression does not occur.
.
.
.Mx
.It Va termcap
(\*(OP) This specifies a comma-separated list of
.Lb libterminfo
and/or
.Lb libtermcap
capabilities (see
.Sx "On terminal control and line editor" ,
escape commas with reverse solidus) to be used to overwrite or define
entries.
.Sy Note
this variable will only be queried once at program startup and can
thus only be specified in resource files or on the command line.
.
.Pp
String capabilities form
.Ql cap=value
pairs and are expected unless noted otherwise.
Numerics have to be notated as
.Ql cap#number
where the number is expected in normal decimal notation.
Finally, booleans do not have any value but indicate a true or false
state simply by being defined or not; this indeed means that \*(UA
does not support undefining an existing boolean.
String capability values will undergo some expansions before use:
for one notations like
.Ql ^LETTER
stand for
.Ql control-LETTER ,
and for clarification purposes
.Ql \eE
can be used to specify
.Ql escape
(the control notation
.Ql ^[
could lead to misreadings when a left bracket follows, which it does for
the standard CSI sequence);
finally three letter octal sequences, as in
.Ql \e061 ,
are supported.
To specify that a terminal supports 256-colours, and to define sequences
that home the cursor and produce an audible bell, one might write:
.
.Bd -literal -offset indent
? set termcap='Co#256,home=\eE[H,bel=^G'
.Ed
.
.Pp
The following terminal capabilities are or may be meaningful for the
operation of the built-in line editor or \*(UA in general:
.
.Pp
.Bl -tag -compact -width ".It Cd yay"
.\" HAVE_COLOUR
.It Cd colors Ns \0or Cd Co
.Cd max_colors :
numeric capability specifying the maximum number of colours.
Note that \*(UA does not actually care about the terminal beside that,
but always emits ANSI / ISO 6429 escape sequences.
.
.\" HAVE_TERMCAP
.It Cd rmcup Ns \0or Cd te Ns \0/ Cd smcup Ns \0or Cd ti
.Cd exit_ca_mode
and
.Cd enter_ca_mode ,
respectively: exit and enter the alternative screen ca-mode,
effectively turning \*(UA into a fullscreen application.
This must be enabled explicitly by setting
.Va termcap-ca-mode .
.
.It Cd smkx Ns \0or Cd ks Ns \0/ Cd rmkx Ns \0or Cd ke
.Cd keypad_xmit
and
.Cd keypad_local ,
respectively: enable and disable the keypad.
This is always enabled if available, because it seems even keyboards
without keypads generate other key codes for, e.g., cursor keys in that
case, and only if enabled we see the codes that we are interested in.
.
.It Cd ed Ns \0or Cd cd
.Cd clr_eos :
clear the screen.
.
.It Cd clear Ns \0or Cd cl
.Cd clear_screen :
clear the screen and home cursor.
(Will be simulated via
.Cd ho
plus
.Cd cd . )
.
.It Cd home Ns \0or Cd ho
.Cd cursor_home :
home cursor.
.
.\" HAVE_MLE
.It Cd el Ns \0or Cd ce
.Cd clr_eol :
clear to the end of line.
(Will be simulated via
.Cd ch
plus repetitions of space characters.)
.
.It Cd hpa Ns \0or Cd ch
.Cd column_address :
move the cursor (to the given column parameter) in the current row.
(Will be simulated via
.Cd cr
plus
.Cd nd . )
.
.It Cd cr
.Cd carriage_return :
move to the first column in the current row.
The default built-in fallback is
.Ql \er .
.
.It Cd cub1 Ns \0or Cd le
.Cd cursor_left :
move the cursor left one space (non-destructively).
The default built-in fallback is
.Ql \eb .
.
.It Cd cuf1 Ns \0or Cd nd
.Cd cursor_right :
move the cursor right one space (non-destructively).
The default built-in fallback is
.Ql \eE[C ,
which is used by most terminals.
Less often occur
.Ql \eEC
and
.Ql \eEOC .
.El
.
.Pp
Many more capabilities which describe key-sequences are documented for
.Ic bind .
.
.
.Mx
.It Va termcap-ca-mode
\*(OP Allow usage of the
.Cd exit_ca_mode
and
.Cd enter_ca_mode
terminal capabilities, effectively turning \*(UA into a fullscreen
application, as documented for
.Va termcap .
.Sy Note
this variable will only be queried once at program startup and can
thus only be specified in resource files or on the command line.
.
.Mx
.It Va termcap-disable
\*(OP Disable any interaction with a terminal control library.
If set only some generic fallback built-ins and possibly the content of
.Va termcap
describe the terminal to \*(UA.
.Sy Note
this variable will only be queried once at program startup and can
thus only be specified in resource files or on the command line.
.
.Mx
.It Va toplines
If defined, gives the number of lines of a message to be displayed
with the command
.Ic top ;
if unset, the first five lines are printed, if set to 0 the variable
.Va screen
is inspected.
If the value is negative then its absolute value will be used for
unsigned right shifting (see
.Ic vexpr )
the
.Va screen
height.
.
.Mx
.It Va topsqueeze
\*(BO If set then the
.Ic top
command series will strip adjacent empty lines and quotations.
.
.Mx
.It Va ttycharset
The character set of the terminal \*(UA operates on,
and the one and only supported character set that \*(UA can use if no
character set conversion capabilities have been compiled into it,
in which case it defaults to ISO-8859-1 unless it can deduce a value
from the locale specified in the
.Ev LC_CTYPE
environment variable (if supported, see there for more).
It defaults to UTF-8 if conversion is available.
Refer to the section
.Sx "Character sets"
for the complete picture about character sets.
.
.Mx
.It Va typescript-mode
\*(BO A special multiplex variable that disables all variables and
settings which result in behaviour that interferes with running \*(UA in
.Xr script 1 ,
e.g., it sets
.Va colour-disable ,
.Va line-editor-disable
and (before startup completed only)
.Va termcap-disable .
Unsetting it does not restore the former state of the covered settings.
.
.Mx
.It Va umask
For a safety-by-default policy \*(UA sets its process
.Xr umask 2
to
.Ql 0077 ,
but this variable can be used to override that:
set it to an empty value to do not change the (current) setting (on
startup), otherwise the process file mode creation mask is updated to
the new value.
Child processes inherit the process file mode creation mask.
.
.Mx Va user
.It Va user-HOST , user
\*(IN Variable chain that sets a global fallback user name, which is
used in case none has been given in the protocol and account-specific
URL.
This variable defaults to the name of the user who runs \*(UA.
.
.Mx
.It Va v15-compat
\*(BO Setting this enables upward compatibility with \*(UA
version 15.0 in respect to which configuration options are available and
how they are handled.
This manual uses \*(IN and \*(OU to refer to the new and the old way of
doing things, respectively.
.
.Mx
.It Va verbose
\*(BO This setting, also controllable via the command line option
.Fl v ,
causes \*(UA to be more verbose, e.g., it will display obsoletion
warnings and SSL/TLS certificate chains.
Even though marked \*(BO this option may be set twice in order to
increase the level of verbosity even more, in which case even details of
the actual message delivery and protocol conversations are shown.
A single
.Pf no Va verbose
is sufficient to disable verbosity as such.
.
.Mx
.Mx
.Mx
.Mx
.Mx
.It Va version , version-date , version-major , version-minor , version-update
\*(RO \*(UA version information: the first variable contains a string
containing the complete version identification, the latter three contain
only digits: the major, minor and update version numbers.
The date is in ISO 8601 notation.
The output of the command
.Ic version
will include this information.
.
.Mx
.It Va writebackedited
If this variable is set messages modified using the
.Ic edit
or
.Ic visual
commands are written back to the current folder when it is quit;
it is only honoured for writable folders in MBOX format, though.
Note that the editor will be pointed to the raw message content in that
case, i.e., neither MIME decoding nor decryption will have been
performed, and proper RFC 4155
.Ql From_
quoting of newly added or edited content is also left as an excercise to
the user.
.El
.\" }}} (Variables)
.
.\" }}} (INTERNAL VARIABLES)
.
.
.\" .Sh ENVIRONMENT {{{
.Sh ENVIRONMENT
.
The term
.Dq environment variable
should be considered an indication that these variables are either
standardized as vivid parts of process environments, or that they are
commonly found in there.
The process environment is inherited from the
.Xr sh 1
once \*(UA is started, and unless otherwise explicitly noted handling of
the following variables transparently integrates into that of the
.Sx "INTERNAL VARIABLES"
from \*(UA's point of view.
This means that, e.g., they can be managed via
.Ic set
and
.Ic unset ,
causing automatic program environment updates (to be inherited by
newly created child processes).
.
.Pp
In order to transparently integrate other environment variables equally
they need to be imported (linked) with the command
.Ic environ .
This command can also be used to set and unset non-integrated
environment variables from scratch, sufficient system support provided.
The following example, applicable to a POSIX shell, sets the
.Ev COLUMNS
environment variable for \*(UA only, and beforehand exports the
.Ev EDITOR
in order to affect any further processing in the running shell:
.
.Bd -literal -offset indent
$ EDITOR="vim -u ${HOME}/.vimrc"
$ export EDITOR
$ COLUMNS=80 \*(uA -R
.Ed
.
.Bl -tag -width ".It Ev BaNg"
.Mx
.It Ev COLUMNS
The user's preferred width in column positions for the terminal screen
or window.
Queried and used once on program startup, actively managed for child
processes and the MLE (see
.Sx "On terminal control and line editor" )
in interactive mode thereafter.
Ignored in non-interactive mode, which always uses 80 columns, unless in
.fl #
batch mode.
.
.Mx
.It Ev DEAD
The name of the (mailbox)
.Ic file
to use for saving aborted messages if
.Va save
is set; this defaults to
.Pa dead.letter
in the user's
.Ev HOME
directory.
If the variable
.Va debug
is set no output will be generated, otherwise the contents of the file
will be replaced.
.
.Mx
.It Ev EDITOR
Pathname of the text editor to use in the
.Ic edit
command and
.Ic ~e
.Sx "COMMAND ESCAPES" .
A default editor is used if this value is not defined.
.
.Mx
.It Ev HOME
The user's home directory.
This variable is only used when it resides in the process environment.
The calling user's home directory will be used instead if this directory
does not exist, is not accessible or cannot be read.
(No test for being writable is performed to allow usage by
non-privileged users within read-only jails, but dependent on the
variable settings this directory is a default write target, e.g. for
.Ev DEAD ,
.Ev MBOX
and more.)
.
.Mx
.Mx
.Mx
.It Ev LC_ALL , LC_CTYPE , LANG
\*(OP The (names in lookup order of the)
.Xr locale 7
(and / or see
.Xr setlocale 3 )
which indicates the used
.Sx "Character sets" .
Runtime changes trigger automatic updates of the entire locale system,
updating and overwriting also a
.Va ttycharset
set by the user.
.
.Mx
.It Ev LINES
The user's preferred number of lines on a page or the vertical screen
or window size in lines.
Queried and used once on program startup, actively managed for child
processes in interactive mode thereafter.
Ignored in non-interactive mode, which always uses 24 lines, unless in
.fl #
batch mode.
.
.Mx
.It Ev LISTER
Pathname of the directory lister to use in the
.Ic folders
command when operating on local mailboxes.
Default is
.Xr ls 1
(path search through
.Ev SHELL ) .
.
.Mx
.It Ev LOGNAME
Upon startup \*(UA will actively ensure that this variable refers to the
name of the user who runs \*(UA, in order to be able to pass a verified
name to any newly created child process.
.
.Mx
.It Ev MAIL
Is used as the users
.Mx -sx
.Sx "primary system mailbox"
unless
.Va inbox
is set.
This is assumed to be an absolute pathname.
.
.Mx
.It Ev MAILCAPS
\*(OP Overrides the default path search for
.Sx "The Mailcap files" ,
which is defined in the standard RFC 1524 as
.Ql ~/.mailcap:\:/etc/mailcap:\:/usr/etc/mailcap:\:/usr/local/etc/mailcap .
.\" TODO we should have a mailcaps-default virtual RDONLY option!
(\*(UA makes it a configuration option, however.)
Note this is not a search path, but a path search.
.
.Mx
.It Ev MAILRC
Is used as a startup file instead of
.Pa \*(ur
if set.
When \*(UA scripts are invoked on behalf of other users,
either this variable should be set to
.Pa /dev/null
or the
.Fl \&:
command line option should be used in order to avoid side-effects from
reading their configuration files.
This variable is only used when it resides in the process environment.
.
.Mx
.It Ev MAILX_NO_SYSTEM_RC
If this variable is set then reading of
.Pa \*(UR
at startup is inhibited, i.e., the same effect is achieved as if \*(UA
had been started up with the option
.Fl \&:
(and according argument) or
.Fl n .
This variable is only used when it resides in the process environment.
.
.Mx
.It Ev MBOX
The name of the users
.Mx -sx
.Sx "secondary mailbox"
file.
A logical subset of the special
.Sx "Filename transformations"
(also see
.Ic file )
are supported.
The default is
.Pa ~/mbox .
Traditionally this MBOX is used as the file to save messages from the
.Mx -sx
.Sx "primary system mailbox"
that have been read.
Also see
.Sx "Message states" .
.
.Mx
.It Ev NETRC
\*(IN\*(OP This variable overrides the default location of the user's
.Pa ~/.netrc
file.
.
.Mx
.It Ev PAGER
Pathname of the program to use for backing the command
.Ic more ,
and when the
.Va crt
variable enforces usage of a pager for output.
The default paginator is
.Xr more 1
(path search through
.Ev SHELL ) .
.Pp
\*(UA inspects the contents of this variable: if its contains the string
.Dq less
then a non-existing environment variable
.Va LESS
will be set to
.Ql FRXi ,
.Ql FRi
or
.Ql Ri ,
dependent on whether terminal control support is available and whether
that supports full (alternative) screen mode or not (also see
.Sx "On terminal control and line editor" ) .
Likewise for
.Dq lv
.Va LV
will optionally be set to
.Dq -c .
Alse see
.Va colour-pager .
.
.Mx
.It Ev PATH
A colon-separated list of directories that is searched by the shell when
looking for commands, e.g.,
.Ql /bin:/usr/bin:/usr/local/bin .
.
.Mx
.It Ev POSIXLY_CORRECT
This variable is automatically looked for upon startup, see
.Va posix
for more.
.
.Mx
.It Ev SHELL
The shell to use for the commands
.Ic \&! ,
.Ic shell ,
the
.Ic ~!
.Sx "COMMAND ESCAPES"
and when starting subprocesses.
A default shell is used if this environment variable is not defined.
.
.Mx
.It Ev SOURCE_DATE_EPOCH
This specifies a time in seconds since the Unix epoch (1970-01-01) to be
used in place of the current time.
This variable is looked up upon program startup, and its existence will
switch \*(UA to a completely reproducible mode which causes
deterministic random numbers, a special fixed (non-existent?)
.Ev LOGNAME
and more to be used and set.
It is to be used during development or by software packagers.
\*(ID Currently an invalid setting is only ignored, rather than causing
a program abortion.
.Pp
.Dl $ SOURCE_DATE_EPOCH=`date +%s` \*(uA
.
.Mx
.It Ev TERM
\*(OP The terminal type for which output is to be prepared.
For extended colour and font control please refer to
.Sx "Coloured display" ,
and for terminal management in general to
.Sx "On terminal control and line editor" .
.
.Mx
.It Ev TMPDIR
Used as directory for temporary files instead of
.Pa /tmp ,
if set, existent, accessible as well as read- and writable.
This variable is only used when it resides in the process environment,
but \*(UA will ensure at startup that this environment variable is
updated to contain a usable temporary directory.
.
.Mx
.It Ev USER
Identical to
.Ev LOGNAME
(see there), but this variable is not standardized, should therefore not
be used, and is only corrected if already set.
.
.Mx
.It Ev VISUAL
Pathname of the text editor to use in the
.Ic visual
command and
.Ic ~v
.Sx "COMMAND ESCAPES" .
.El
.
.\" }}}
.
.
.\" .Sh FILES {{{
.Sh FILES
.
.\" file list {{{
.Bl -tag -width ".It Pa BaNg"
.It Pa \*(ur
File giving initial commands, one of the
.Sx "Resource files" .
.
.It Pa \*(UR
System wide initialization file, one of the
.Sx "Resource files" .
.
.Mx
.It Pa ~/.mailcap
\*(OP Personal MIME type handler definition file, see
.Sx "The Mailcap files" .
This location is part of the RFC 1524 standard search path, which is
a configuration option and can be overridden via
.Ev MAILCAPS .
.
.Mx
.It Pa /etc/mailcap
\*(OP System wide MIME type handler definition file, see
.Sx "The Mailcap files" .
This location is part of the RFC 1524 standard search path, which is
a configuration option and can be overridden via
.
.Mx
.It Pa ~/mbox
The default value for
.Ev MBOX .
The actually used path is a configuration option.
.
.Mx
.It Pa ~/.mime.types
Personal MIME types, see
.Sx "The mime.types files" .
The actually used path is a configuration option.
.
.Mx
.It Pa /etc/mime.types
System wide MIME types, see
.Sx "The mime.types files" .
The actually used path is a configuration option.
.
.Mx
.It Pa ~/.netrc
\*(IN\*(OP The default location of the users
.Pa .netrc
file \(en the section
.Sx "The .netrc file"
documents the file format.
The actually used path is a configuration option and can be overridden via
.Ev NETRC .
.
.Mx
.It Pa /dev/null
The data sink
.Xr null 4 .
The actually used path is a compile-time constant.
.El
.\" }}}
.
.\" .Ss "Resource files" {{{
.Ss "Resource files"
.
Upon startup \*(UA reads in several resource files:
.
.Bl -tag -width ".It Pa BaNg"
.Mx
.It Pa \*(UR
System wide initialization file.
Reading of this file can be suppressed, either by using the
.Fl \&:
(and according argument) or
.Fl n
command line options, or by setting the
.Sx ENVIRONMENT
variable
.Ev MAILX_NO_SYSTEM_RC .
.
.Mx
.It Pa \*(ur
File giving initial commands.
A different file can be chosen by setting the
.Sx ENVIRONMENT
variable
.Ev MAILRC .
Reading of this file can be suppressed with the
.Fl \&:
command line option.
.
.It Va mailx-extra-rc
Defines a startup file to be read after all other resource files.
It can be used to specify settings that are not understood by other
.Xr mailx 1
implementations, for example.
This variable is only honoured when defined in a resource file, e.g.,
it is one of the
.Sx "INTERNAL VARIABLES" .
.El
.
.Pp
The content of these files is interpreted as follows:
.
.Pp
.Bl -bullet -compact
.It
The whitespace characters space, tabulator and newline,
as well as those defined by the variable
.Va ifs ,
are removed from the beginning and end of input lines.
.It
Empty lines are ignored.
.It
Any other line is interpreted as a command.
It may be spread over multiple input lines if the newline character is
.Dq escaped
by placing a reverse solidus character
.Ql \e
as the last character of the line; whereas any leading whitespace of
follow lines is ignored, trailing whitespace before a escaped newline
remains in the input.
.It
If the line (content) starts with the number sign
.Ql #
then it is a comment-command and also ignored.
(The comment-command is a real command, which does nothing, and
therefore the usual follow lines mechanism applies!)
.El
.
.Pp
Unless \*(UA is about to enter interactive mode syntax errors that occur
while loading these files are treated as errors and cause program exit.
More files with syntactically equal content can be
.Ic source Ns ed .
The following, saved in a file, would be an examplary content:
.
.Bd -literal -offset indent
 # This line is a comment command.  And y\e
    es, it is really continued here.
set debug \e
    verbose
    set editheaders
.Ed
.\" }}}
.
.\" .Ss "The mime.types files" {{{
.Ss "The mime.types files"
.
As stated in
.Sx "HTML mail and MIME attachments"
\*(UA needs to learn about MIME (Multipurpose Internet Mail Extensions)
media types in order to classify message and attachment content.
One source for them are
.Pa mime.types
files, the loading of which can be controlled by setting the variable
.Va mimetypes-load-control .
Another is the command
.Ic mimetype ,
which also offers access to \*(UAs MIME type cache.
.Pa mime.types
files have the following syntax:
.
.Bd -literal -offset indent
type/subtype extension [extension ...]
# E.g., text/html html htm
.Ed
.
.Pp
where
.Ql type/subtype
define the MIME media type, as standardized in RFC 2046:
.Ql type
is used to declare the general type of data, while the
.Ql subtype
specifies a specific format for that type of data.
One or multiple filename
.Ql extension Ns
s, separated by whitespace, can be bound to the media type format.
Comments may be introduced anywhere on a line with a number sign
.Ql # ,
causing the remaining line to be discarded.
.
\*(UA also supports an extended, non-portable syntax in especially
crafted files, which can be loaded via the alternative value syntax of
.Va mimetypes-load-control ,
and prepends an optional
.Ql type-marker :
.
.Pp
.Dl [type-marker ]type/subtype extension [extension ...]
.
.Pp
The following type markers are supported:
.
.Pp
.Bl -tag -compact -width ".It Ar _n_u"
.It Ar @
Treat message parts with this content as plain text.
.It Ar @t
The same as plain
.Ar @ .
.It Ar @h
Treat message parts with this content as HTML tagsoup.
If the \*(OPal HTML-tagsoup-to-text converter is not available treat
the content as plain text instead.
.It Ar @H
Likewise
.Ar @h ,
but instead of falling back to plain text require an explicit content
handler to be defined.
.El
.
.Pp
Further reading:
for sending messages:
.Ic mimetype ,
.Va mime-allow-text-controls ,
.Va mimetypes-load-control .
For reading etc. messages:
.Sx "HTML mail and MIME attachments" ,
.Sx "The Mailcap files" ,
.Ic mimetype ,
.Va mime-counter-evidence ,
.Va mimetypes-load-control ,
.Va pipe-TYPE/SUBTYPE ,
.Va pipe-EXTENSION .
.\" }}}
.
.\" .Ss "The Mailcap files" {{{
.Ss "The Mailcap files"
.
.\" TODO MAILCAP DISABLED
.Sy This feature is not available in v14.9.0, sorry!
RFC 1524 defines a
.Dq User Agent Configuration Mechanism
which \*(UA \*(OPally supports (see
.Sx "HTML mail and MIME attachments" ) .
It defines a file format to be used to inform mail user agent programs
about the locally-installed facilities for handling various data
formats, i.e., about commands and how they can be used to display, edit
et cetera MIME part contents, as well as a default path search that
includes multiple possible locations of
.Dq mailcap
files and the
.Ev MAILCAPS
environment variable that can be used to overwrite that (repeating here
that it is not a search path, but instead a path search specification).
Any existing files will be loaded in sequence, appending any content to
the list of MIME type handler directives.
.
.Pp
.Dq Mailcap
files consist of a set of newline separated entries.
Comment lines start with a number sign
.Ql #
(in the first column!) and are ignored.
Empty lines are also ignored.
All other lines form individual entries that must adhere to the syntax
described below.
To extend a single entry (not comment) its line can be continued on
follow lines if newline characters are
.Dq escaped
by preceding them with the reverse solidus character
.Ql \e .
The standard does not specify how leading whitespace of follow lines
is to be treated, therefore \*(UA retains it.
.
.Pp
.Dq Mailcap
entries consist of a number of semicolon
.Ql \&;
separated fields, and the reverse solidus
.Ql \e
character can be used to escape any following character including
semicolon and itself.
The first two fields are mandatory and must occur in the specified
order, the remaining fields are optional and may appear in any order.
Leading and trailing whitespace of content is ignored (removed).
.
.Pp
The first field defines the MIME
.Ql TYPE/SUBTYPE
the entry is about to handle (case-insensitively, and no reverse solidus
escaping is possible in this field).
If the subtype is specified as an asterisk
.Ql *
the entry is meant to match all subtypes of the named type, e.g.,
.Ql audio/*
would match any audio type.
The second field defines the shell command which shall be used to
.Dq display
MIME parts of the given type; it is implicitly called the
.Cd view
command.
.
.Pp
For data
.Dq consuming
shell commands message (MIME part) data is passed via standard input
unless the given shell command includes one or more instances of the
(unquoted) string
.Ql %s ,
in which case these instances will be replaced with a temporary filename
and the data will have been stored in the file that is being pointed to.
Likewise, for data
.Dq producing
shell commands data is assumed to be generated on standard output unless
the given command includes (one ore multiple)
.Ql %s .
In any case any given
.Ql %s
format is replaced with a(n already) properly quoted filename.
Note that when a command makes use of a temporary file via
.Ql %s
then \*(UA will remove it again, as if the
.Cd x-mailx-tmpfile ,
.Cd x-mailx-tmpfile-fill
and
.Cd x-mailx-tmpfile-unlink
flags had been set; see below for more.
.
.Pp
The optional fields either define a shell command or an attribute (flag)
value, the latter being a single word and the former being a keyword
naming the field followed by an equals sign
.Ql =
succeeded by a shell command, and as usual for any
.Dq Mailcap
content any whitespace surrounding the equals sign will be removed, too.
Optional fields include the following:
.
.
.Bl -tag -width ".It Cd BaNg"
.It Cd compose
A program that can be used to compose a new body or body part in the
given format.
(Currently unused.)
.
.It Cd composetyped
Similar to the
.Cd compose
field, but is to be used when the composing program needs to specify the
.Ql Content-type:
header field to be applied to the composed data.
(Currently unused.)
.
.It Cd edit
A program that can be used to edit a body or body part in the given
format.
(Currently unused.)
.
.It Cd print
A program that can be used to print a message or body part in the given
format.
(Currently unused.)
.
.It Cd test
Specifies a program to be run to test some condition, e.g., the machine
architecture, or the window system in use, to determine whether or not
this mailcap entry applies.
If the test fails, a subsequent mailcap entry should be sought; also see
.Cd x-mailx-test-once .
.
.Mx
.It Cd needsterminal
This flag field indicates that the given shell command must be run on
an interactive terminal.
\*(UA will temporarily release the terminal to the given command in
interactive mode, in non-interactive mode this entry will be entirely
ignored; this flag implies
.Cd x-mailx-noquote .
.
.Mx
.It Cd copiousoutput
A flag field which indicates that the output of the
.Cd view
command will be an extended stream of textual output that can be
(re)integrated into \*(UA's normal visual display.
It is mutually exclusive with
.Cd needsterminal .
.
.It Cd textualnewlines
A flag field which indicates that this type of data is line-oriented and
that, if encoded in
.Ql base64 ,
all newlines should be converted to canonical form (CRLF) before
encoding, and will be in that form after decoding.
(Currently unused.)
.
.It Cd nametemplate
This field gives a filename format, in which
.Ql %s
will be replaced by a random string, the joined combination of which
will be used as the filename denoted by
.Ev MAILX_FILENAME_TEMPORARY .
One could specify that a GIF file being passed to an image viewer should
have a name ending in
.Ql .gif
by using
.Ql nametemplate=%s.gif .
Note that \*(UA ignores the name template unless that solely specifies
a filename suffix that consists of (ASCII) alphabetic and numeric
characters, the underscore and dot only.
.
.It Cd x11-bitmap
Names a file, in X11 bitmap (xbm) format, which points to an appropriate
icon to be used to visually denote the presence of this kind of data.
This field is not used by \*(UA.
.
.It Cd description
A textual description that describes this type of data.
.
.Mx
.It Cd x-mailx-even-if-not-interactive
An extension flag test field \(em by default handlers without
.Cd copiousoutput
are entirely ignored in non-interactive mode, but if this flag is set
then their use will be considered.
It is an error if this flag is set for commands that use the flag
.Cd needsterminal .
.
.Mx
.It Cd x-mailx-noquote
An extension flag field that indicates that even a
.Cd copiousoutput
.Cd view
command shall not be used to generate message quotes
(as it would be by default).
.
.Mx
.It Cd x-mailx-async
Extension flag field that denotes that the given
.Cd view
command shall be executed asynchronously, without blocking \*(UA.
Cannot be used in conjunction with
.Cd needsterminal .
.
.Mx
.It Cd x-mailx-test-once
Extension flag which denotes whether the given
.Cd test
command shall be evaluated once only and the (boolean) result be cached.
This is handy if some global unchanging condition is to be queried, like
.Dq running under the X Window System .
.
.Mx
.It Cd x-mailx-tmpfile
Extension flag field that requests creation of a zero-sized temporary
file, the name of which is to be placed in the environment variable
.Ev MAILX_FILENAME_TEMPORARY .
It is an error to use this flag with commands that include a
.Ql %s
format.
.
.Mx
.It Cd x-mailx-tmpfile-fill
Normally the MIME part content is passed to the handler via standard
input; if this flag is set then the data will instead be written into
the implied
.Cd x-mailx-tmpfile .
In order to cause deletion of the temporary file you will have to set
.Cd x-mailx-tmpfile-unlink
explicitly!
It is an error to use this flag with commands that include a
.Ql %s
format.
.
.Mx
.It Cd x-mailx-tmpfile-unlink
Extension flag field that requests that the temporary file shall be
deleted automatically when the command loop is entered again at latest.
(Do not use this for asynchronous handlers.)
It is an error to use this flag with commands that include a
.Ql %s
format, or in conjunction with
.Cd x-mailx-async ,
or without also setting
.Cd x-mailx-tmpfile
or
.Cd x-mailx-tmpfile-fill .
.
.Mx
.It Cd x-mailx-tmpfile-keep
Using the string
.Ql %s
implies the three tmpfile related flags above, but if you want, e.g.,
.Cd x-mailx-async
and deal with the temporary file yourself, you can add in this flag to
forcefully ignore
.Cd x-mailx-tmpfile-unlink .
.El
.
.
.Pp
The standard includes the possibility to define any number of additional
entry fields, prefixed by
.Ql x- .
Flag fields apply to the entire
.Dq Mailcap
entry \(em in some unusual cases, this may not be desirable, but
differentiation can be accomplished via separate entries, taking
advantage of the fact that subsequent entries are searched if an earlier
one does not provide enough information.
E.g., if a
.Cd view
command needs to specify the
.Cd needsterminal
flag, but the
.Cd compose
command shall not, the following will help out the latter (with enabled
.Va debug
or an increased
.Va verbose
level \*(UA will show information about handler evaluation):
.
.Bd -literal -offset indent
application/postscript; ps-to-terminal %s; needsterminal
application/postscript; ps-to-terminal %s; compose=idraw %s
.Ed
.
.Pp
In fields any occurrence of the format string
.Ql %t
will be replaced by the
.Ql TYPE/SUBTYPE
specification.
Named parameters from the
.Ql Content-type:
field may be placed in the command execution line using
.Ql %{
followed by the parameter name and a closing
.Ql }
character.
The entire parameter should appear as a single command line argument,
regardless of embedded spaces; thus:
.
.Bd -literal -offset indent
# Message
Content-type:  multipart/mixed; boundary=42

# Mailcap file
multipart/*; /usr/local/bin/showmulti \e
  %t %{boundary}  ;  composetyped  = /usr/local/bin/makemulti

# Executed shell command
/usr/local/bin/showmulti multipart/mixed 42
.Ed
.
.Pp
.\" TODO v15: Mailcap: %n,%F
Note that \*(UA does not support handlers for multipart MIME parts as
shown in this example (as of today).
\*(UA does not support the additional formats
.Ql %n
and
.Ql %F .
An example file, also showing how to properly deal with the expansion of
.Ql %s ,
which includes any quotes that are necessary to make it a valid shell
argument by itself and thus will cause undesired behaviour when placed
in additional user-provided quotes:
.
.Bd -literal -offset indent
# Comment line
text/richtext; richtext %s; copiousoutput

text/x-perl; perl -cWT %s

application/pdf; \e
  infile=%s\e; \e
    trap "rm -f ${infile}" EXIT\e; \e
    trap "exit 75" INT QUIT TERM\e; \e
    mupdf %s; \e
  x-mailx-async; x-mailx-tmpfile-keep

application/*; echo "This is \e"%t\e" but \e
    is 50 \e% Greek to me" \e; < %s head -c 1024 | cat -vET; \e
  copiousoutput; x-mailx-noquote
.Ed
.
.Pp
Further reading:
.Sx "HTML mail and MIME attachments" ,
.Sx "The mime.types files" ,
.Ic mimetype ,
.Ev MAILCAPS ,
.Va mime-counter-evidence ,
.Va pipe-TYPE/SUBTYPE ,
.Va pipe-EXTENSION .
.\" }}}
.
.\" .Ss "The .netrc file" {{{
.Ss "The .netrc file"
.
The
.Pa .netrc
file contains user credentials for machine accounts.
The default location in the user's
.Ev HOME
directory may be overridden by the
.Ev NETRC
environment variable.
The file consists of space, tabulator or newline separated tokens.
\*(UA implements a parser that supports a superset of the original BSD
syntax, but users should nonetheless be aware of portability glitches
of that file format, shall their
.Pa .netrc
be usable across multiple programs and platforms:
.
.Pp
.Bl -bullet -compact
.It
BSD does not support single, but only double quotation marks, e.g.,
.Ql password="pass with spaces" .
.It
BSD (only?) supports escaping of single characters via a reverse solidus
(e.g., a space can be escaped via
.Ql \e\0 ) ,
in- as well as outside of a quoted string.
.It
BSD does not require a final quotation mark of the last user input token.
.It
The original BSD (Berknet) parser also supported a format which allowed
tokens to be separated with commas \(en whereas at least Hewlett-Packard
still seems to support this syntax, \*(UA does not!
.It
As a non-portable extension some widely-used programs support
shell-style comments: if an input line starts, after any amount of
whitespace, with a number sign
.Ql # ,
then the rest of the line is ignored.
.It
Whereas other programs may require that the
.Pa .netrc
file is accessible by only the user if it contains a
.Cd password
token for any other
.Cd login
than
.Dq anonymous ,
\*(UA will always require these strict permissions.
.El
.
.Pp
Of the following list of supported tokens \*(UA only uses (and caches)
.Cd machine ,
.Cd login
and
.Cd password .
At runtime the command
.Ic netrc
can be used to control \*(UA's
.Pa .netrc
cache.
.
.Bl -tag -width ".It Cd BaNg"
.It Cd machine Ar name
The hostname of the entries' machine, lowercase-normalized by \*(UA
before use.
Any further file content, until either end-of-file or the occurrence
of another
.Cd machine
or a
.Cd default
first-class token is bound (only related) to the machine
.Ar name .
.Pp
As an extension that should not be the cause of any worries
\*(UA supports a single wildcard prefix for
.Ar name :
.Bd -literal -offset indent
machine *.example.com login USER password PASS
machine pop3.example.com login USER password PASS
machine smtp.example.com login USER password PASS
.Ed
.Pp
which would match
.Ql xy.example.com
as well as
.Ql pop3.example.com ,
but neither
.Ql example.com
nor
.Ql local.smtp.example.com .
Note that in the example neither
.Ql pop3.example.com
nor
.Ql smtp.example.com
will be matched by the wildcard, since the exact matches take
precedence (it is however faster to specify it the other way around).
.
.It Cd default
This is the same as
.Cd machine
except that it is a fallback entry that is used shall none of the
specified machines match; only one default token may be specified,
and it must be the last first-class token.
.
.It Cd login Ar name
The user name on the remote machine.
.
.It Cd password Ar string
The user's password on the remote machine.
.
.It Cd account Ar string
Supply an additional account password.
This is merely for FTP purposes.
.
.It Cd macdef Ar name
Define a macro.
A macro is defined with the specified
.Ar name ;
it is formed from all lines beginning with the next line and continuing
until a blank line is (consecutive newline characters are) encountered.
(Note that
.Cd macdef
entries cannot be utilized by multiple machines, too, but must be
defined following the
.Ic machine
they are intended to be used with.)
If a macro named
.Ar init
exists, it is automatically run as the last step of the login process.
This is merely for FTP purposes.
.El
.\" }}}
.
.\" }}}
.
.
.\" .Sh EXAMPLES {{{
.Sh EXAMPLES
.
.\" .Ss "An example configuration" {{{
.Ss "An example configuration"
.
.Bd -literal -offset indent
# This example assumes v15.0 compatibility mode
set v15-compat

# Request strict transport security checks!
set ssl-verify=strict

# Where are the up-to-date SSL certificates?
# (Since we manage up-to-date ones explicitly, do not use any,
# possibly outdated, default certificates shipped with OpenSSL)
#set ssl-ca-dir=/etc/ssl/certs
set ssl-ca-file=/etc/ssl/certs/ca-certificates.crt
set ssl-ca-no-defaults
#set ssl-ca-flags=partial-chain
wysh set smime-ca-file="${ssl-ca-file}" \e
  smime-ca-no-defaults #smime-ca-flags="${ssl-ca-flags}"

# Do not use protocols older than TLS v1.2.
# Change this only when the remote server does not support it:
# maybe use ssl-protocol-HOST (or -USER@HOST) syntax to define
# such explicit exceptions, then, e.g.
#   set ssl-protocol-exam.ple='-ALL,+TLSv1.1'
set ssl-protocol='-ALL,+TLSv1.2'

# Explicitly define the list of ciphers, which may improve security,
# especially with protocols older than TLS v1.2.  See ciphers(1).
# Including "@STRENGTH" will sort the final list by algorithm strength.
# In reality it is possibly best to only use ssl-cipher-list-HOST
# (or -USER@HOST), as necessary, again..
set ssl-cipher-list=TLSv1.2:!aNULL:!eNULL:@STRENGTH

# - TLSv1.2:!aNULL:!eNULL:\e
#     ECDHE-RSA-AES256-SHA:ECDHE-ECDSA-AES256-SHA:\e
#     DHE-RSA-AES256-SHA:@STRENGTH
# -ALL:!aNULL:!eNULL:!MEDIUM:!LOW:!MD5:!RC4:!EXPORT:@STRENGTH
# Especially with TLSv1.3 curves selection may be desired:
#set ssl-curves=P-521:P-384:P-256

# Essential setting: select allowed character sets
set sendcharsets=utf-8,iso-8859-1

# A very kind option: when replying to a message, first try to
# use the same encoding that the original poster used herself!
set reply-in-same-charset

# When replying, do not merge From: and To: of the original message
# into To:.  Instead old From: -> new To:, old To: -> merge Cc:.
set recipients-in-cc

# When sending messages, wait until the Mail-Transfer-Agent finishs.
# Only like this you will be able to see errors reported through the
# exit status of the MTA (including the built-in SMTP one)!
set sendwait

# Only use built-in MIME types, no mime.types(5) files
set mimetypes-load-control

# Default directory where we act in (relative to $HOME)
set folder=mail
# A leading "+" (often) means: under *folder*
# *record* is used to save copies of sent messages
set MBOX=+mbox.mbox DEAD=+dead.txt \e
  record=+sent.mbox record-files record-resent

# Make "file mymbox" and "file myrec" go to..
shortcut mymbox %:+mbox.mbox myrec +sent.mbox

# Not really optional, e.g., for S/MIME
set from='Your Name <address@exam.ple>'

# It may be necessary to set hostname and/or smtp-hostname
# if the "SERVER" of mta and "domain" of from do not match.
# The `urlencode' command can be used to encode USER and PASS
set mta=(smtps?|submission)://[USER[:PASS]@]SERVER[:PORT] \e
  smtp-auth=login/plain... \e
  smtp-use-starttls

# Never refuse to start into interactive mode, and more
set emptystart \e
  colour-pager crt= \e
  followup-to followup-to-honour=ask-yes \e
  history-file=+.\*(uAhist history-size=-1 history-gabby \e
  mime-counter-evidence=0xE \e
  prompt='?\e?!\e![\e${account}#\e${mailbox-display}]? ' \e
  reply-to-honour=ask-yes \e
  umask=

# Only include the selected header fields when typing messages
headerpick type retain from_ date from to cc subject \e
  message-id mail-followup-to reply-to
# ...when forwarding messages
headerpick forward retain subject date from to cc
# ...when saving message, etc.
#headerpick save ignore ^Original-.*$ ^X-.*$

# Some mailing lists
mlist '@xyz-editor\e.xyz$' '@xyzf\e.xyz$'
mlsubscribe '^xfans@xfans\e.xyz$'

# Handle a few file extensions (to store MBOX databases)
filetype bz2 'bzip2 -dc' 'bzip2 -zc' \e
  gz 'gzip -dc' 'gzip -c'  xz 'xz -dc' 'xz -zc' \e
  zst 'zstd -dc' 'zstd -19 -zc' \e
  zst.pgp 'gpg -d | zstd -dc' 'zstd -19 -zc | gpg -e'

# A real life example of a very huge free mail provider
# Instead of directly placing content inside `account',
# we `define' a macro: like that we can switch "accounts"
# from within *on-compose-splice*, for example!
define XooglX {
  set folder=~/spool/XooglX inbox=+syste.mbox sent=+sent
  set from='Your Name <address@examp.ple>'
  set mta=smtp://USER:PASS@smtp.gmXil.com smtp-use-starttls
}
account XooglX {
  \ecall XooglX
}

# Here is a pretty large one which does not allow sending mails
# if there is a domain name mismatch on the SMTP protocol level,
# which would bite us if the value of from does not match, e.g.,
# for people who have a sXXXXeforge project and want to speak
# with the mailing list under their project account (in from),
# still sending the message through their normal mail provider
define XandeX {
  set folder=~/spool/XandeX inbox=+syste.mbox sent=+sent
  set from='Your Name <address@exam.ple>'
  set mta=smtps://USER:PASS@smtp.yaXXex.ru:465 \e
    hostname=yaXXex.com smtp-hostname=
}
account XandeX {
  \ecall Xandex
}

# Create some new commands so that, e.g., `ls /tmp' will..
commandalias lls '!ls ${LS_COLOR_FLAG} -aFlrS'
commandalias llS '!ls ${LS_COLOR_FLAG} -aFlS'

# We do not support gpg(1) directly yet.  But simple --clearsign'd
# message parts can be dealt with as follows:
define V {
  localopts yes
  wysh set pipe-text/plain=$'@*#++=@\e
    < "${MAILX_FILENAME_TEMPORARY}" awk \e
        -v TMPFILE="${MAILX_FILENAME_TEMPORARY}" \e'\e
      BEGIN{done=0}\e
      /^-----BEGIN PGP SIGNED MESSAGE-----/,/^$/ {\e
        if(done++ != 0)\e
          next;\e
        print "--- GPG --verify ---";\e
        system("gpg --verify " TMPFILE " 2>&1");\e
        print "--- GPG --verify ---";\e
        print "";\e
        next;\e
      }\e
      /^-----BEGIN PGP SIGNATURE-----/,\e
          /^-----END PGP SIGNATURE-----/{\e
        next;\e
      }\e
      {print}\e
    \e''
    print
}
commandalias V '\e'call V
.Ed
.
.Pp
When storing passwords in
.Pa \*(ur
appropriate permissions should be set on this file with
.Ql $ chmod 0600 \*(ur .
If the \*(OPal
.Va netrc-lookup
is available user credentials can be stored in the central
.Pa .netrc
file instead; e.g., here is a different version of the example account
that sets up SMTP and POP3:
.
.Bd -literal -offset indent
define XandeX {
  set folder=~/spool/XandeX inbox=+syste.mbox sent=+sent
  set from='Your Name <address@exam.ple>'
  set netrc-lookup
  # Load an encrypted ~/.netrc by uncommenting the next line
  #set netrc-pipe='gpg -qd ~/.netrc.pgp'

  set mta=smtps://smtp.yXXXXx.ru:465 \e
      smtp-hostname= hostname=yXXXXx.com
  set pop3-keepalive=240 pop3-no-apop-pop.yXXXXx.ru
  commandalias xp fi pop3s://pop.yXXXXx.ru
}
account XandeX {
  \ecall XandeX
}
.Ed
.
.Pp
and, in the
.Pa .netrc
file:
.
.Bd -literal -offset indent
machine *.yXXXXx.ru login USER password PASS
.Ed
.
.Pp
This configuration should now work just fine:
.
.Pp
.Dl $ echo text | \*(uA -dvv -AXandeX -s Subject user@exam.ple
.\" }}}
.
.\" .Ss "S/MIME step by step" {{{
.Ss "S/MIME step by step"
.
\*(OP The first thing you need for participating in S/MIME message
exchange is your personal certificate, including a private key.
The certificate contains public information, in particular your name and
your email address(es), and the public key that is used by others to
encrypt messages for you,
and to verify signed messages they supposedly received from you.
The certificate is included in each signed message you send.
The private key must be kept secret.
It is used to decrypt messages that were previously encrypted with your
public key, and to sign messages.
.
.Pp
For personal use it is recommended that you get a S/MIME certificate
from one of the major CAs on the Internet using your WWW browser.
Many CAs offer such certificates for free.
There is also
.Lk https://www.CAcert.org
which issues client and server certificates to members of their
community for free; their root certificate
.Pf ( Lk https://\:www.cacert.org/\:certs/\:root.crt )
is often not in the default set of trusted CA root certificates, though,
which means you will have to download their root certificate separately
and ensure it is part of our S/MIME certificate validation chain by
including it in
.Va smime-ca-dir
or as a vivid member of the
.Va smime-ca-file .
But let us take a step-by-step tour on how to setup S/MIME with
a certificate from CAcert.org despite this situation!
.
.Pp
First of all you will have to become a member of the CAcert.org
community, simply by registrating yourself via the web interface.
Once you are, create and verify all email addresses you want to be able
to create signed and encrypted messages for/with using the corresponding
entries of the web interface.
Now ready to create S/MIME certificates, so let us create a new
.Dq client certificate ,
ensure to include all email addresses that should be covered by the
certificate in the following web form, and also to use your name as the
.Dq common name .
.
.Pp
Create a private key and a certificate request on your local computer
(please see the manual pages of the used commands for more in-depth
knowledge on what the used arguments etc. do):
.
.Pp
.Dl $ openssl req -nodes -newkey rsa:4096 -keyout key.pem -out creq.pem
.
.Pp
Afterwards copy-and-paste the content of
.Dq creq.pem
into the certificate-request (CSR) field of the web form on the
CAcert.org website (you may need to unfold some
.Dq advanced options
to see the corresponding text field).
This last step will ensure that your private key (which never left your
box) and the certificate belong together (through the public key that
will find its way into the certificate via the certificate-request).
You are now ready and can create your CAcert certified certificate.
Download and store or copy-and-paste it as
.Dq pub.crt .
.
.Pp
Yay.
In order to use your new S/MIME setup a combined private key/public key
(certificate) file has to be created:
.
.Pp
.Dl $ cat key.pem pub.crt > ME@HERE.com.paired
.
.Pp
This is the file \*(UA will work with.
If you have created your private key with a passphrase then \*(UA will
ask you for it whenever a message is signed or decrypted.
Set the following variables to henceforth use S/MIME (setting
.Va smime-ca-file
is of interest for verification only):
.
.Bd -literal -offset indent
? set smime-ca-file=ALL-TRUSTED-ROOT-CERTS-HERE \e
    smime-sign-cert=ME@HERE.com.paired \e
    smime-sign-message-digest=SHA256 \e
    smime-sign
.Ed
.
.\" }}}
.
.\" .Ss "Using CRLs with S/MIME or SSL/TLS" {{{
.Ss "Using CRLs with S/MIME or SSL/TLS"
.
\*(OP Certification authorities (CAs) issue certificate revocation
lists (CRLs) on a regular basis.
These lists contain the serial numbers of certificates that have been
declared invalid after they have been issued.
Such usually happens because the private key for the certificate has
been compromised,
because the owner of the certificate has left the organization that is
mentioned in the certificate, etc.
To seriously use S/MIME or SSL/TLS verification,
an up-to-date CRL is required for each trusted CA.
There is otherwise no method to distinguish between valid and
invalidated certificates.
\*(UA currently offers no mechanism to fetch CRLs, nor to access them on
the Internet, so they have to be retrieved by some external mechanism.
.
.Pp
\*(UA accepts CRLs in PEM format only;
CRLs in DER format must be converted, like, e.\|g.:
.
.Pp
.Dl $ openssl crl \-inform DER \-in crl.der \-out crl.pem
.
.Pp
To tell \*(UA about the CRLs, a directory that contains all CRL files
(and no other files) must be created.
The
.Va smime-crl-dir
or
.Va ssl-crl-dir
variables, respectively, must then be set to point to that directory.
After that, \*(UA requires a CRL to be present for each CA that is used
to verify a certificate.
.\" }}}
.
.\" }}} (Examples)
.
.
.\" .Sh "FAQ" {{{
.Sh "FAQ"
.
In general it is a good idea to turn on
.Va debug
.Pf ( Fl d )
and / or
.Va verbose
.Pf ( Fl v ,
twice) if something does not work well.
Very often a diagnostic message can be produced that leads to the
problems' solution.
.
.\" .Ss "\*(UA shortly hangs on startup" {{{
.Ss "\*(UA shortly hangs on startup"
.
This can have two reasons, one is the necessity to wait for a file lock
and cannot be helped, the other being that \*(UA calls the function
.Xr uname 2
in order to query the nodename of the box (sometimes the real one is
needed instead of the one represented by the internal variable
.Va hostname ) .
One may have varying success by ensuring that the real hostname and
.Ql localhost
have entries in
.Pa /etc/hosts ,
or, more generally, that the name service is properly setup \(en
and does
.Xr hostname 1
return the expected value?
Does this local hostname have a domain suffix?
RFC 6762 standardized the link-local top-level domain
.Ql .local ,
try again after adding an (additional) entry with this extension.
.\" }}}
.
.\" .Ss "I cannot login to Google mail aka GMail" {{{
.Ss "I cannot login to Google mail aka GMail"
.
Since 2014 some free service providers classify programs as
.Dq less secure
unless they use a special authentification method (OAuth 2.0) which
was not standardized for non-HTTP protocol authentication token query
until August 2015 (RFC 7628).
.
.Pp
Different to Kerberos / GSSAPI, which is developed since the mid of the
1980s, where a user can easily create a local authentication ticket for
her- and himself with the locally installed
.Xr kinit 1
program, that protocol has no such local part but instead requires
a world-wide-web query to create or fetch a token; since there is no
local cache this query would have to be performed whenever \*(UA is
invoked (in interactive sessions situation may differ).
.
.Pp
\*(UA does not support OAuth.
Because of this it is necessary to declare \*(UA a
.Dq less secure app
(on the providers account web page) in order to read and send mail.
However, it also seems possible to take the following steps instead:
.
.Pp
.Bl -enum -compact
.It
give the provider the number of a mobile phone,
.It
enable
.Dq 2-Step Verification ,
.It
create an application specific password (16 characters), and
.It
use that special password instead of the real Google account password in
\*(UA (for more on that see the section
.Sx "On URL syntax and credential lookup" ) .
.El
.\" }}}
.
.\" .Ss "Not \(dqdefunctional\(dq, but the editor key does not work" {{{
.Ss "Not \(dqdefunctional\(dq, but the editor key does not work"
.
It can happen that the terminal library (see
.Sx "On terminal control and line editor",
.Ic bind ,
.Va termcap )
reports different codes than the terminal really sends, in which case
\*(UA will tell that a key binding is functional, but will not be able to
recognize it because the received data does not match anything expected.
Especially without the \*(OPal terminal capability library support one
reason for this may be that the (possibly even non-existing) keypad
is not turned on and the resulting layout reports the keypad control
codes for the normal keyboard keys.
The
.Va verbose
listing of
.Ic bind Ns
ings will show the byte sequences that are expected.
.
.Pp
To overcome the situation, use, e.g., the program
.Xr cat 1 ,
in conjunction with the command line option
.Fl \&\&v ,
if available, to see the byte sequences which are actually produced
by keypresses, and use the variable
.Va termcap
to make \*(UA aware of them.
E.g., the terminal this is typed on produces some false sequences, here
an example showing the shifted home key:
.
.Bd -literal -offset indent
? set verbose
? bind*
# 1B 5B=[ 31=1 3B=; 32=2 48=H
  bind base :kHOM z0
? x
$ cat -v
^[[H
? \*(uA -v -Stermcap='kHOM=\eE[H'
? bind*
# 1B 5B=[ 48=H
  bind base :kHOM z0
.Ed
.\" }}}
.
.\" }}}
.
.
.\" .Sh "IMAP CLIENT" {{{
.Sh "IMAP CLIENT"
.
\*(OPally there is IMAP client support available.
This part of the program is obsolete and will vanish in v15 with the
large MIME and I/O layer rewrite, because it uses old-style blocking I/O
and makes excessive use of signal based long code jumps.
Support can hopefully be readded later based on a new-style I/O, with
SysV signal handling.
In fact the IMAP support had already been removed from the codebase, but
was reinstantiated on user demand: in effect the IMAP code is at the
level of \*(UA v14.8.16 (with
.Ic imapcodec
being the sole exception), and should be treated with some care.
.
.Pp
IMAP uses the
.Ql imap://
and
.Ql imaps://
protocol prefixes, and an IMAP-based
.Va folder
may be used.
IMAP URLs (paths) undergo inspections and possible transformations
before use (and the command
.Ic imapcodec
can be used to manually apply them to any given argument).
Hierarchy delimiters are normalized, a step which is configurable via the
.Va imap-delim
variable chain, but defaults to the first seen delimiter otherwise.
\*(UA supports internationalised IMAP names, and en- and decodes the
names from and to the
.Va ttycharset
as necessary and possible.
If a mailbox name is expanded (see
.Sx "Filename transformations" )
to an IMAP mailbox, all names that begin with `+' then refer to IMAP
mailboxes below the
.Va folder
target box, while folder names prefixed by `@' refer to folders below
the hierarchy base.
.
.Pp
Note: some IMAP servers do not accept the creation of mailboxes in
the hierarchy base, but require that they are created as subfolders of
`INBOX' \(en with such servers a folder name of the form
.Pp
.Dl imaps://mylogin@imap.myisp.example/INBOX.
.Pp
should be used (the last character is the server's hierarchy
delimiter).
The following IMAP-specific commands exist:
.
.
.Bl -tag -width ".It Ic BaNg"
.Mx
.It Ic cache
Only applicable to cached IMAP mailboxes;
takes a message list and reads the specified messages into the IMAP
cache.
.
.Mx
.It Ic connect
If operating in disconnected mode on an IMAP mailbox,
switch to online mode and connect to the mail server while retaining
the mailbox status.
See the description of the
.Va disconnected
variable for more information.
.
.Mx
.It Ic disconnect
If operating in online mode on an IMAP mailbox,
switch to disconnected mode while retaining the mailbox status.
See the description of the
.Va disconnected
variable for more.
A list of messages may optionally be given as argument;
the respective messages are then read into the cache before the
connection is closed, thus
.Ql disco *
makes the entire mailbox available for disconnected use.
.
.Mx
.It Ic imap
Sends command strings directly to the current IMAP server.
\*(UA operates always in IMAP `selected state' on the current mailbox;
commands that change this will produce undesirable results and should be
avoided.
Useful IMAP commands are:
.Bl -tag -offset indent -width ".Ic getquotearoot"
.It create
Takes the name of an IMAP mailbox as an argument and creates it.
.It getquotaroot
(RFC 2087) Takes the name of an IMAP mailbox as an argument
and prints the quotas that apply to the mailbox.
Not all IMAP servers support this command.
.It namespace
(RFC 2342) Takes no arguments and prints the Personal Namespaces,
the Other User's Namespaces and the Shared Namespaces.
Each namespace type is printed in parentheses;
if there are multiple namespaces of the same type,
inner parentheses separate them.
For each namespace a prefix and a hierarchy separator is listed.
Not all IMAP servers support this command.
.El
.
.Mx
.It Ic imapcodec
Perform IMAP path transformations.
Supports
.Cm vput
(see
.Sx "Command modifiers" ) ,
and manages the error number
.Va \&! .
The first argument specifies the operation:
.Ar e[ncode]
normalizes hierarchy delimiters (see
.Va imap-delim )
and converts the strings from the locale
.Va ttycharset
to the internationalized variant used by IMAP,
.Ar d[ecode]
performs the reverse operation.
.El
.
.
.Pp
The following IMAP-specific internal variables exist:
.
.
.Bl -tag -width ".It Va BaNg"
.Mx
.It Va disconnected
\*(BO When an IMAP mailbox is selected and this variable is set,
no connection to the server is initiated.
Instead, data is obtained from the local cache (see
.Va imap-cache Ns
).
Mailboxes that are not present in the cache
and messages that have not yet entirely been fetched from the server
are not available;
to fetch all messages in a mailbox at once,
the command
.No ` Ns Li copy * /dev/null Ns '
can be used while still in connected mode.
Changes that are made to IMAP mailboxes in disconnected mode are queued
and committed later when a connection to that server is made.
This procedure is not completely reliable since it cannot be guaranteed
that the IMAP unique identifiers (UIDs) on the server still match the
ones in the cache at that time.
Data is saved to
.Ev DEAD
when this problem occurs.
.
.It Va disconnected-USER@HOST
The specified account is handled as described for the
.Va disconnected
variable above,
but other accounts are not affected.
.
.Mx Va imap-auth
.It Va imap-auth-USER@HOST , imap-auth
Sets the IMAP authentication method.
Valid values are `login' for the usual password-based authentication
(the default),
`cram-md5', which is a password-based authentication that does not send
the password over the network in clear text,
and `gssapi' for GSS-API based authentication.
.
.Mx
.It Va imap-cache
Enables caching of IMAP mailboxes.
The value of this variable must point to a directory that is either
existent or can be created by \*(UA.
All contents of the cache can be deleted by \*(UA at any time;
it is not safe to make assumptions about them.
.
.Mx Va imap-delim
.It Va imap-delim-USER@HOST , imap-delim-HOST , imap-delim
The hierarchy separator used by the IMAP server.
Whenever an IMAP path is specified it will undergo normalization.
One of the normalization steps is the squeezing and adjustment of
hierarchy separators.
If this variable is set, any occurrence of any character of the given
value that exists in the path will be replaced by the first member of
the value; an empty value will cause the default to be used, it is
.Ql /. .
If not set, we will reuse the first hierarchy separator character that
is discovered in a user-given mailbox name.
.
.Mx Va imap-keepalive
.It Va imap-keepalive-USER@HOST , imap-keepalive-HOST , imap-keepalive
IMAP servers may close the connection after a period of
inactivity; the standard requires this to be at least 30 minutes,
but practical experience may vary.
Setting this variable to a numeric `value' greater than 0 causes
a `NOOP' command to be sent each `value' seconds if no other operation
is performed.
.
.Mx
.It Va imap-list-depth
When retrieving the list of folders on an IMAP server, the
.Ic folders
command stops after it has reached a certain depth to avoid possible
infinite loops.
The value of this variable sets the maximum depth allowed.
The default is 2.
If the folder separator on the current IMAP server is a slash `/',
this variable has no effect and the
.Ic folders
command does not descend to subfolders.
.
.Mx Va imap-use-starttls
.It Va imap-use-starttls-USER@HOST , imap-use-starttls-HOST , imap-use-starttls
Causes \*(UA to issue a `STARTTLS' command to make an unencrypted
IMAP session SSL/TLS encrypted.
This functionality is not supported by all servers,
and is not used if the session is already encrypted by the IMAPS method.
.El
.
.\" }}}
.
.
.\" .Sh "SEE ALSO" {{{
.Sh "SEE ALSO"
.
.Xr bogofilter 1 ,
.Xr gpg 1 ,
.Xr more 1 ,
.Xr newaliases 1 ,
.Xr openssl 1 ,
.Xr sendmail 1 ,
.Xr sh 1 ,
.Xr spamassassin 1 ,
.Xr iconv 3 ,
.Xr setlocale 3 ,
.Xr aliases 5 ,
.Xr termcap 5 ,
.Xr terminfo 5 ,
.Xr locale 7 ,
.Xr mailaddr 7 ,
.Xr re_format 7 ,
.Xr mailwrapper 8 ,
.Xr sendmail 8
.
.\" }}}
.
.
.\" .Sh HISTORY {{{
.Sh HISTORY
.
M. Douglas McIlroy writes in his article
.Dq A Research UNIX Reader: Annotated Excerpts \
from the Programmer's Manual, 1971-1986
that a
.Xr mail 1
command already appeared in First Edition
.Ux
in 1971:
.
.Bd -ragged -offset indent
Electronic mail was there from the start.
Never satisfied with its exact behavior, everybody touched it at one
time or another: to assure the safety of simultaneous access, to improve
privacy, to survive crashes, to exploit uucp, to screen out foreign
freeloaders, or whatever.
Not until v7 did the interface change (Thompson).
Later, as mail became global in its reach, Dave Presotto took charge and
brought order to communications with a grab-bag of external networks
(v8).
.Ed
.
.Pp
.Bx
Mail was written in 1978 by Kurt Shoens and developed as part of the
.Bx
.Ux
distribution until 1995.
Mail has then seen further development in open source
.Bx
variants, noticeably by Christos Zoulas in
.Pf Net Bx .
Based upon this Nail, later Heirloom Mailx, was developed by Gunnar
Ritter in the years 2000 until 2008.
Since 2012 S-nail is maintained by Steffen (Daode) Nurpmeso.
This man page is derived from
.Dq The Mail Reference Manual
that was originally written by Kurt Shoens.
.
.\" }}}
.
.
.Sh AUTHORS
.
.An "Kurt Shoens" ,
.An "Edward Wang" ,
.An "Keith Bostic" ,
.An "Christos Zoulas" ,
.An "Gunnar Ritter" ,
.An "Steffen Nurpmeso" .
.
.Pp
The variables
.Va contact-mail
and
.Va contact-web
provide contact addresses:
.Pp
.\" v15-compat: drop eval as `mail' will expand variable?
.Dl ? echo $contact-web; eval mail $contact-mail
.
.
.\" .Sh CAVEATS {{{
.Sh CAVEATS
.
\*(ID Interrupting an operation via
.Dv \&\&SIGINT
aka
.Ql control-C
from anywhere else but a command prompt is very problematic and likely
to leave the program in an undefined state: many library functions
cannot deal with the
.Fn siglongjmp 3
that this software (still) performs; even though efforts have been taken
to address this, no sooner but in v15 it will have been worked out:
interruptions have not been disabled in order to allow forceful breakage
of hanging network connections, for example (all this is unrelated to
.Va ignore ) .
.
.Pp
The SMTP and POP3 protocol support of \*(UA is very basic.
Also, if it fails to contact its upstream SMTP server, it will not make
further attempts to transfer the message at a later time (setting
.Va save
and
.Va sendwait
may be useful).
If this is a concern, it might be better to set up a local SMTP server
that is capable of message queuing.
.
.\" }}}
.
.
.Sh BUGS
.
After deleting some message of a POP3 mailbox the header summary falsely
claims that there are no messages to display, one needs to perform
a scroll or dot movement to restore proper state.
.
In threaded display a power user may encounter crashes very
occasionally (this is may and very).
.
The file
.Pa TODO
in the source repository lists future directions.
.
.\" s-ts-mode