mail.sh

   1 #! /bin/sh
   2 # source: mail.sh
   3 # Copyright Gerhard Rieger and contributors (see file CHANGES)
   4 # Published under the GNU General Public License V.2, see file COPYING
   5
   6 #set -vx
   7
   8 # This is an example for a shell script that can be fed to socat with exec.
   9 # Its clue is that it does not use stdin/stdout for communication with socat,
  10 # so you may feed the mail message via stdin to the script. The message should
  11 # contain appropriate mail headers without continuation lines.
  12 # socat establishes the connection to the SMTP server; the script performs the
  13 # SMTP dialog and afterwards transfers the message body to the server.
  14 # Lines with only a dot are not permitted - use two dots as escape.
  15 # This script supports multiline answers from server, but not much more yet.
  16
  17 # Usage:  cat message.txt |socat exec:"mail.sh target@domain.com",fdin=3,fdout=4 tcp:mail.relay.org:25,crlf
  18
  19 while [ "$1" ]; do
  20     case "$1" in
  21     -f) shift; mailfrom="$1"; shift;;
  22     *) break;;
  23     esac
  24 done
  25
  26 rcptto="$1"
  27 [ -z "$1" ] && rcptto="root@loopback"
  28 #server=$(expr "$rcptto" : '[^@]*@\(.*\)')
  29 [ -z "$mailfrom" ] && mailfrom="$USER@$(hostname)"
  30
  31 # this function waits for a complete server message, checks if its status
  32 # is in the permitted range (terminates session if not), and returns.
  33 mail_chat () {
  34     local cmd="$1"
  35     local errlevel="$2";  [ -z "$errlevel" ] && errlevel=300
  36
  37     if [ "$cmd" ]; then  echo "> $cmd" >&2;  fi
  38     if [ -n "$cmd" ]; then echo "$cmd" >&4; fi
  39     while read status message <&3;
  40         (
  41             case "$status" in
  42             [0-9][0-9][0-9]-*) exit 0;;
  43             [0-9][0-9][0-9]*) exit 1;;
  44             *) exit 1;;
  45             esac
  46         )
  47     do :; done
  48     if [ -z "$status" ]; then  echo smtp connection failed >&2; exit;  fi
  49     echo "< $status $message" >&2
  50     if [ "$status" -ge "$errlevel" ]; then
  51         echo $message >&2
  52         echo "QUIT" >&4; exit 1
  53     fi
  54 }
  55
  56
  57 # expect server greeting
  58 mail_chat
  59
  60 mail_chat "HELO $(hostname)"
  61
  62 mail_chat "MAIL FROM: $mailfrom"
  63
  64 mail_chat "RCPT TO: $rcptto"
  65
  66 mail_chat "DATA" 400
  67
  68 while read l; do echo "$l" >&4; done
  69 mail_chat "."
  70
  71 mail_chat "QUIT"
  72
  73 exit 0