sendmail

#!/usr/bin/env python

import sys, os
import argparse
from subprocess import call

helpmsg="""Simple sendmail wrapper for pmail.

Unknown arguments are ignored. Messages are read from stdin by default
(like the sendmail -t argument). All unknown arguments that don't start
with '-' and do contain '@' are presumed to be recepients.

Delivers to SMTP server on localhost by default.
"""
parser = argparse.ArgumentParser(description=helpmsg,
                                 formatter_class=argparse.RawDescriptionHelpFormatter)
parser.add_argument('dest_addr', help='Destination Address',
                    metavar='foo@example.com', nargs='?',
                    default=None)
parser.add_argument('-bcc',
                    help='BCC Address. Can be specified multiple times.',
                    metavar='foo@example.com', action='append')
parser.add_argument('-f', '-F',
                    help='From address. For envelope. Sets From header '+
                    'if absent from message.',
                    metavar='me@example.com', dest='from_addr')

args, unknown = parser.parse_known_args()

if args.from_addr:
    from_addr = args.from_addr
else:
    import os, pwd
    for le in ['MAILSUSER', 'MAILUSER', 'LOGNAME', 'LOGUSER', 'USER']:
        from_addr = os.environ.get(le, None)
        if from_addr: break
    if not from_addr:
        from_addr = pwd.getpwuid(os.geteuid()).pw_name

dom=None
for le in ['MAILSHOST', 'MAILHOST']:
    dom = os.environ.get(le, None)
    if dom: break
if not dom:
    import socket
    dom = socket.getfqdn()

if '@' not in from_addr:
    from_addr = from_addr + '@' + dom

# use localhost and set exim up in a smarthost configuration.
cmd = ['pmail', '-n', '--server', 'localhost']
if args.bcc:
  for x in args.bcc:
    cmd.extend(["-b", x])
if from_addr:
  cmd.extend(["-f", from_addr])

if args.dest_addr:
  if '@' in args.dest_addr:
    dest_addr = args.dest_addr
  else:
    dest_addr = args.dest_addr + '@' + dom
  unknown.insert(0, dest_addr)

if unknown:
  for x in unknown:
    if not x[0] == '-' and '@' in x:
      cmd.extend(["-t", x])

call(cmd,stdin=sys.stdin)

sys.exit(0)


"""
# rules for envelope from (http://www.courier-mta.org/sendmail.html)
#sendmail constructs the envelope sender (the return address), userid@host as
#follows, unless the -bs option was specified. If the -bs option is specified
#the envelope sender is specified via ESMTP commands, of course.
#
#If the -f option was specified, the address specified by the -f option is
#  used.
#
#Otherwise, the userid portion of the return address is set to the contents of
#the first environment variable that's defined from the following list:
#MAILSUSER, MAILUSER, LOGNAME, LOGUSER. If none of these environment variables
#are defined, the system account name is used.
#
#The host portion of the return address is set to the contents of the
#MAILSHOST environment variable. If MAILSHOST is not defined, MAILHOST will be
#used. If neither variable is set, the configured machine name is used.

TODO: Construct envelope and from from the same env vars that sendmail does in
case some script (namely script that expect local delivery) use them.

# rules for From:
#If the From: header is present in the message, but the environment variable
#MAILUSER is set, the userid portion of the From: header is replaced by the
#contents of MAILUSER.
#
#If the From: header is present in the message, but the MAILHOST environment
#variable is set, the contents of MAILHOST replaces the host portion of the
#From: header.
#
#If the From: header is present in the message, but either the -F option was
#specified, or the MAILNAME or the NAME environment variable is set, the
#contents of the -F option, or the environment variable, will replace the
#sender's name in the From: header.
#
#If the From: header is not present in the message, one is constructed as
#follows. The sender's name is set by the -F option. If the -F option was
#not specified, the contents of the MAILNAME or the NAME environment
#variable is used. If neither variable is used, the name is looked up from
#the system account file. The userid portion of the address is set by the
#contents of any one of the following environment variables: MAILUSER,
#LOGNAME, USER. If none of these variables are set, the system userid is
#used. The host portion of the address is set by the contents of the
#MAILHOST environment variable. If it is not set, the system name of the
#server is used.
"""