[Mailman-Users] Tangent: Exporting information from Mailman to the MTA

Jay A. Sekora jsekora at csail.mit.edu
Mon May 23 17:18:30 CEST 2011

On Mon, 2011-05-23 at 15:03 +0900, Stephen J. Turnbull wrote:
> Of course, some things have to involve Mailman (eg, filtering posts on
> list membership).  But even there, the developers consider it a design
> bug that Mailman has no way to export its member database to filtering
> software at the MTA level (which would make it possible to reject a
> post based on the From: nonmember + To: list combination without ever
> accepting the mail, among many other potential applications).  This is
> being remedied in Mailman 3.

I haven't been following Mailman 3 development plans, and that's good to
hear!  I've been intending to do this out of a cron job, so that Exim
can refuse at SMTP time mail that it knows the destination list would
refuse anyway.

That reminds me of something I've sort of been wishing for for a bit,
which would be the ability to expose arbitrary new list-specific
variables to list admins which would be stored in the list pickle.  The
obvious example is a SpamAssassin threshold over which to refuse mail to
the list.  We have lots of standard general-purpose lists, but we also
have some lists which *discuss* spam and/or security threats, which need
a higher score.  Other examples would be a list of languages the list
accepts, what sorts of attachments to allow, and the like.

Obviously, there are other ways to get this sort of information to the
MTA and/or filtering software, but treating these things as list
attributes, with the same web interface as all the other list
attributes, would make things easy on list maintainers.  I'm guessing
this sort of thing is not possible without code changes to Mailman
(forgive my lack of understanding of the Mailman codebase), but if the
web UI is in whole or in part programmatically generated, it might be
possible already -- and if not, a way for site or list administrators to
add arbitrary variables to a list (even if the Mailman codebase doesn't
do anything with them itself) might be a useful feature to consider for
Mailman 3, especially if there's a general facility for making them
available to MTAs.  (For all I know, of course, this may already be in
the works.)


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