Doc/lib/libpoplib.tex

   1 \section{\module{poplib} ---
   2          POP3 protocol client}
   3
   4 \declaremodule{standard}{poplib}
   5 \modulesynopsis{POP3 protocol client (requires sockets).}
   6
   7 %By Andrew T. Csillag
   8 %Even though I put it into LaTeX, I cannot really claim that I wrote
   9 %it since I just stole most of it from the poplib.py source code and
  10 %the imaplib ``chapter''.
  11 %Revised by ESR, January 2000
  12
  13 \indexii{POP3}{protocol}
  14
  15 This module defines a class, \class{POP3}, which encapsulates a
  16 connection to a POP3 server and implements the protocol as defined in
  17 \rfc{1725}.  The \class{POP3} class supports both the minimal and
  18 optional command sets. Additionally, this module provides a class
  19 \class{POP3_SSL}, which provides support for connecting to POP3
  20 servers that use SSL as an underlying protocol layer.
  21
  22
  23 Note that POP3, though widely supported, is obsolescent.  The
  24 implementation quality of POP3 servers varies widely, and too many are
  25 quite poor. If your mailserver supports IMAP, you would be better off
  26 using the \code{\refmodule{imaplib}.\class{IMAP4}} class, as IMAP
  27 servers tend to be better implemented.
  28
  29 A single class is provided by the \module{poplib} module:
  30
  31 \begin{classdesc}{POP3}{host\optional{, port}}
  32 This class implements the actual POP3 protocol.  The connection is
  33 created when the instance is initialized.
  34 If \var{port} is omitted, the standard POP3 port (110) is used.
  35 \end{classdesc}
  36
  37 \begin{classdesc}{POP3_SSL}{host\optional{, port\optional{, keyfile\optional{, certfile}}}}
  38 This is a subclass of \class{POP3} that connects to the server over an
  39 SSL encrypted socket.  If \var{port} is not specified, 995, the
  40 standard POP3-over-SSL port is used.  \var{keyfile} and \var{certfile}
  41 are also optional - they can contain a PEM formatted private key and
  42 certificate chain file for the SSL connection.
  43
  44 \versionadded{2.4}
  45 \end{classdesc}
  46
  47 One exception is defined as an attribute of the \module{poplib} module:
  48
  49 \begin{excdesc}{error_proto}
  50 Exception raised on any errors.  The reason for the exception is
  51 passed to the constructor as a string.
  52 \end{excdesc}
  53
  54 \begin{seealso}
  55   \seemodule{imaplib}{The standard Python IMAP module.}
  56   \seetitle[http://www.catb.org/\~{}esr/fetchmail/fetchmail-FAQ.html]
  57         {Frequently Asked Questions About Fetchmail}
  58         {The FAQ for the \program{fetchmail} POP/IMAP client collects
  59          information on POP3 server variations and RFC noncompliance
  60          that may be useful if you need to write an application based
  61          on the POP protocol.}
  62 \end{seealso}
  63
  64
  65 \subsection{POP3 Objects \label{pop3-objects}}
  66
  67 All POP3 commands are represented by methods of the same name,
  68 in lower-case; most return the response text sent by the server.
  69
  70 An \class{POP3} instance has the following methods:
  71
  72
  73 \begin{methoddesc}{set_debuglevel}{level}
  74 Set the instance's debugging level.  This controls the amount of
  75 debugging output printed.  The default, \code{0}, produces no
  76 debugging output.  A value of \code{1} produces a moderate amount of
  77 debugging output, generally a single line per request.  A value of
  78 \code{2} or higher produces the maximum amount of debugging output,
  79 logging each line sent and received on the control connection.
  80 \end{methoddesc}
  81
  82 \begin{methoddesc}{getwelcome}{}
  83 Returns the greeting string sent by the POP3 server.
  84 \end{methoddesc}
  85
  86 \begin{methoddesc}{user}{username}
  87 Send user command, response should indicate that a password is required.
  88 \end{methoddesc}
  89
  90 \begin{methoddesc}{pass_}{password}
  91 Send password, response includes message count and mailbox size.
  92 Note: the mailbox on the server is locked until \method{quit()} is
  93 called.
  94 \end{methoddesc}
  95
  96 \begin{methoddesc}{apop}{user, secret}
  97 Use the more secure APOP authentication to log into the POP3 server.
  98 \end{methoddesc}
  99
 100 \begin{methoddesc}{rpop}{user}
 101 Use RPOP authentication (similar to UNIX r-commands) to log into POP3 server.
 102 \end{methoddesc}
 103
 104 \begin{methoddesc}{stat}{}
 105 Get mailbox status.  The result is a tuple of 2 integers:
 106 \code{(\var{message count}, \var{mailbox size})}.
 107 \end{methoddesc}
 108
 109 \begin{methoddesc}{list}{\optional{which}}
 110 Request message list, result is in the form
 111 \code{(\var{response}, ['mesg_num octets', ...], \var{octets})}.
 112 If \var{which} is set, it is the message to list.
 113 \end{methoddesc}
 114
 115 \begin{methoddesc}{retr}{which}
 116 Retrieve whole message number \var{which}, and set its seen flag.
 117 Result is in form  \code{(\var{response}, ['line', ...], \var{octets})}.
 118 \end{methoddesc}
 119
 120 \begin{methoddesc}{dele}{which}
 121 Flag message number \var{which} for deletion.  On most servers
 122 deletions are not actually performed until QUIT (the major exception is
 123 Eudora QPOP, which deliberately violates the RFCs by doing pending
 124 deletes on any disconnect).
 125 \end{methoddesc}
 126
 127 \begin{methoddesc}{rset}{}
 128 Remove any deletion marks for the mailbox.
 129 \end{methoddesc}
 130
 131 \begin{methoddesc}{noop}{}
 132 Do nothing.  Might be used as a keep-alive.
 133 \end{methoddesc}
 134
 135 \begin{methoddesc}{quit}{}
 136 Signoff:  commit changes, unlock mailbox, drop connection.
 137 \end{methoddesc}
 138
 139 \begin{methoddesc}{top}{which, howmuch}
 140 Retrieves the message header plus \var{howmuch} lines of the message
 141 after the header of message number \var{which}. Result is in form
 142 \code{(\var{response}, ['line', ...], \var{octets})}.
 143
 144 The POP3 TOP command this method uses, unlike the RETR command,
 145 doesn't set the message's seen flag; unfortunately, TOP is poorly
 146 specified in the RFCs and is frequently broken in off-brand servers.
 147 Test this method by hand against the POP3 servers you will use before
 148 trusting it.
 149 \end{methoddesc}
 150
 151 \begin{methoddesc}{uidl}{\optional{which}}
 152 Return message digest (unique id) list.
 153 If \var{which} is specified, result contains the unique id for that
 154 message in the form \code{'\var{response}\ \var{mesgnum}\ \var{uid}},
 155 otherwise result is list \code{(\var{response}, ['mesgnum uid', ...],
 156 \var{octets})}.
 157 \end{methoddesc}
 158
 159 Instances of \class{POP3_SSL} have no additional methods. The
 160 interface of this subclass is identical to its parent.
 161
 162
 163 \subsection{POP3 Example \label{pop3-example}}
 164
 165 Here is a minimal example (without error checking) that opens a
 166 mailbox and retrieves and prints all messages:
 167
 168 \begin{verbatim}
 169 import getpass, poplib
 170
 171 M = poplib.POP3('localhost')
 172 M.user(getpass.getuser())
 173 M.pass_(getpass.getpass())
 174 numMessages = len(M.list()[1])
 175 for i in range(numMessages):
 176     for j in M.retr(i+1)[1]:
 177         print j
 178 \end{verbatim}
 179
 180 At the end of the module, there is a test section that contains a more
 181 extensive example of usage.