[Mailman-Users] Writing a custom handler

[Chris Nulk]

Hello user,

I am writing a custom handler to globally ban email address from sending 
messages sent to Mailman.  I know I can use Mark's add_banned.py script 
to add an address to all lists.  However, if I add an address to be 
banned, as the administrator for all lists, I don't want a list admin to 
remove a pest from their list(s).  I banned an address for being a pest 
to all lists (or a majority of them), therefore, the address stays banned.

Before I put the custom handler in place and screw up my lists, I 
thought I would post it here so others more knowledgeable can review it 
and let me know if it will work, correct it, and/or improve it.

Thanks,
Chris

--------------------------- Custom Handler Below 
-------------------------------

#!/usr/bin/env python
#

"""This is a custom handler that will check all the sender addresses of
a message against a global ban list.  If any of the sender addresses are
on the global ban list, the message will get logged and discarded.
"""

import sys

from Mailman import mm_cfg
from Mailman import Utils
from Mailman import Message
from Mailman import Errors
from Mailman.i18n import _
from Mailman.Logging.Syslog import syslog
from Mailman.MailList import MailList

def process(mlist, msg, msgdata):
     # added because it was in Mailman/Handlers/Moderate.py
     #   I am guessing it has to due in part with an upstream
     #   pipeline handler marking the message approved and/or
     #   because the handler can be moved to different parts
     #   of the pipeline.
     #   But, I have been wrong before.
     if msgdata.get('approved') or msgdata.get('fromusenet'):
         return

     # First, initialize the banlist
     banlist = []

     # Read in the global ban list of email addresses
     #  mm_cfg.GLOBALBANLIST_FILENAME is defined in mm_cfg and should
     #  be the full path to the file.
     try:
         with open(mm_cfg.GLOBALBANLIST_FILENAME) as f:
             for addr in f:
                 banlist.append(addr.lower().strip())
     except IOError:
         # cannot open the global ban list for whatever reason
         # log it and continue with the next pipeline handler
         syslog('error', 'An error occurred opening the global ban list')
         return
     except:
         # unspecified error
         # log it and continue with the next pipeline handler
         syslog('error', "ERROR: Unknown error: ", sys.exc_info()[0])
         return

     # Go through possible senders.  Check if any of them are
     #   on the global ban list
     for sender in msg.get_senders():
         if sender.lower() in banlist:
             break
     else:
         # None of the sender addresses were in the global ban
         #   list so return and continue with the next pipeline
         #   handler
         return

     # A sender was found on the global ban list.  Log it and
     #   discard the message notifying the list owner
     if sender:
         # Log banned sender to the vette log
         syslog('vette', '%s is banned by the global ban list', sender)
         # Perform message discard
         do_discard_globalban(mlist, msg)
     else:
         assert 0, 'Bad sender in GlobalBan.py'


# copied almost verbatim from Mailman/Handlers/Moderate.py
def do_discard_globalban(mlist, msg):
     sender = msg.get_sender
     # forward auto-discards to list owners?
     if mlist.forward_auto_discards:
         lang = mlist.preferred_language
         # is varhelp used anywhere?
         varhelp = '%s/?VARHELP=privacy/sender/discard_these_nonmembers' % \
                   mlist.GetScriptURL('admin', absolute=1)
         nmsg = Message.UserNotification(mlist.GetOwnerEmail(),
                                         mlist.GetBouncesEmail(),
                                         _('Global Ban List Auto-discard 
notification'),
                                         lang=lang)
         nmsg.set_type('multipart/mixed')
         text = MIMEText(Utils.wrap(_("""\
The sender of the attached message is on the Global Ban list. Therefore, 
the message
has been automatically discarded.""")),
                         _charset=Utils.GetCharSet(lang))
         nmsg.attach(text)
         nmsg.attach(MIMEMessage(msg))
         nmsg.send(mlist)
     # Discard the message
     raise Errors.DiscardMessage