[Mailman-Developers] anti-spam filter

[Ian Eiloart]

On 15 Apr 2013, at 11:22, Stephen J. Turnbull <stephen at xemacs.org> wrote:

> OTOH, a generic interface to the Mailman REST API, which could be used
> by Sendmail milters or whatever else is out there and somewhat
> standard (is it Postfix or Exim that can handle milters? I forget),
> with example implementation of a milter that checks whether the poster
> is subscribed by asking Mailman, would be useful as an extension to
> any MTA used with Mailman.

I think Mailman supports SMTP/LMTP calls to discover whether a sender is permitted to post to a list, doesn't it?

Exim doesn't handle Milters, but can do the calls forward. Provided Mailman is making the judgement, and issuing L/SMTP rejects at L/SMTP time before accepting the message, Exim is fine.

Content filtering *could* also be done at L/SMTP time. I think that where the Mailman and the MTA installations are managed by the same person or organisation, then the better place to have content filtering performed is at the MTA, but there might be exceptions to this.

For example, a medical mailing list might want to be more liberal with regard to drugs that are commonly marketed in spam. Conversely, a list might have a particular subscriber demographic that makes it more sensitive to bad language. Or perhaps different lists might have different primary languages, and therefore different views on the value of messages in that language.

So, I can see that different lists on the same system might have different requirements for spam filtering. However, the solution is probably to provide hooks into Spamassassin, or another existing spam solution, and to provide ways that list owners can manage a configuration file on a per list basis.

-- 
Ian Eiloart
Postmaster, University of Sussex
+44 (0) 1273 87-3148