The Mailgate v2 configuration language

I have decided to overhaul mailgate in a major way. Here's the proposed new
configuration syntax.

Note: Parts of this syntax are shamelessly stolen from
      Eric S Raymond's fetchmail!


1) setting global options

  mboxdir is 'dir name'|None    # dir of mbox files
  savedir is 'dir name'|None    # dir of saved mboxes
  errordir is 'dir name'        # dir of saved messages in case of delivery errors
  Postmaster is 'address'       # Postmaster's email address

2) getting mail from a POP account

  input from POP3 | APOP at 'mail server' 
  user 'username' password 'password'
    [keep]                      # keep mail in POP account
    [for 'domain']              # forward mails to this domain

3) getting mail from an mbox file

  input from mbox in 'mbox file'
    [for 'domain']

4) sending mail with SMTP

  output with SMTP to 'mail server'

5) sending mail to an mbox file

  output to mbox 'mbox file'    # always appends

6) specifying redirections

  redirect all to 'recipient' [and 'recipient']... ,
    'pattern' to 'recipient' [and 'recipient']... ,
    header 'field name' with 'pattern' to ...

  alternative:

  redirect
    recipient '^bb-exec@dware.ch$' to prog '/usr/local/bin/mail-exec',
    recipient 'mhc@dware.ch' to mbox 'dware.mbx'
    from '@spammer.com$' to mbox '/dev/null'
    sender 'linux-kernel' to SMTP 'lk'
    domain 'dware.ch' to SMTP 'mail.intern.dware.ch'

7) specifying a schedule

  schedule days Mon-Fri, hours 7-21, minutes 10, 30, 50
  schedule days Sat, Sun hours 10, 14, 18 minutes 0
  
  if no schedule is given, mailgate just runs once.

8) executing a batch

  .                             # that's right: a single dot!

9) ignored tokens: and, at, by, from, in, is, to, with, ':'


This whole thing will use the Python module tokenize to parse
the config file.


Examples:

# ex mailgate.py
errordir is '.'
Postmaster is 'Postmaster@dware.ch'

input POP3 from 'pop.spectraweb.ch'
  user 'dware1' with password 'secret'
  for domain 'dware.ch'
redirect
  '^dware1?@spectraweb.ch$' to Postmaster,
  '^root@dwaf01' to 'bb',
  'crypto-gram|livid|linux|opendvd|ovd-dev' to 'bb',
  '@golem\.de$' to 'bb' and 'aw',
  '^house66' to 'bb' 'mba' 'aw' 'bud',
  '^bb-priv' to 'beat.bolli@earthling.net'
  # etc...
output with SMTP to 'mail.intern.dware.ch'.
	 
	 
input POP3 from 'pop.bluewin.ch'
  user 'beat.bolli' password 'blabla'
redirect all to 'bb'
output with SMTP to 'mail'
option u.

# ex POPMbox.py
mboxdir is '\\DWAS21\DO\Daten\PM\Mail_in\POP2Mbox'

input POP3 form 'mail.intern.dware.ch' user 'mhc' password 'secret2'
output to mbox 'mhc.mbx'.

input POP3 form 'mail.intern.dware.ch' user 'info' password 'secret3'
output to mbox 'info.mbx'.

# ex MboxSMTP.py
mboxdir is '\\DWAS21\DO\Daten\PM\Mail_out\Mbox2SMTP'
savedir is '\\DWAS21\DO\Daten\PM\Mail_out\Mbox2SMTP\save'

input from mbox 'dware.mbx' domain 'dware.ch'
output with SMTP to 'mail.intern.dware.ch'.