[Mailman-Users] Mailman bounce counters and delivery of spam

Mark Sapiro mark at msapiro.net
Sun Jan 31 17:03:52 CET 2010

Albert ARIBAUD wrote:
>Well, I can't argue that in this instance free.fr does a better job of
>detecting spam than the list, but a) free.fr does not provide mailing
>lists beyond the most basic functionality, and b) I'm not in position to
>suggest moving the list as I'm not the owner, only a member.
>Regarding your suggestion of better spam detection at the earliest
>stage, I agree wholeheartedly. But while I might be able to suggest
>mailman settings to the list owner, heavier actions such as changing the
>spam detection methods in place on the list are out of question.

So you agree that the problem is that the management of the Mailman
installation and/or the list is not effective in keeping spam off the
list, but you ask us change Mailman to solve it.

Note that if the list server had spam detection as effective as yours,
there would be no problem. Perhaps you can change your own spam
detection to just drop rather than reject a message with Precedence:

Anyway, a request to change Mailman to mitigate the effects of
ineffective management is not necessarily unreasonable, but I think it
is in this case. The definition of a 550 in both RFCs 2821 and 5321 is:

   550  Requested action not taken: mailbox unavailable (e.g., mailbox
      not found, no access, or command rejected for policy reasons)

You ask that any 550 (or 5xx) that mentions spam be ignored by Mailman,
but what about all those 550s generated with text like "Service
Unavailable" or other generic reasons which I suspect are as common in
rejections of spam as reasons that mention spam specifically.

Mailman's bounce recognition is already overloaded with kludges and
heuristics. Adding even more for this is not going to happen.

And, my suggestion to change your spam detection is only intended to
encourage you to think about what a can of worms you'd be opening when
you try to do things like this.

As far as suggesting changes to the owner goes, what is the list's
policy for non-member posts? Discarding or Holding them blocks a lot
of spam. Rejecting is bad because it will bounce spam to the From:
address which is certainly forged, and Accepting just invites spam on
the list. Also, if the list allows subscription without admin
approval, new members should be moderated by default.

If the list is active (at least 1 post per day) and spam is only
delivered every second or third day, setting bounce_info_stale_after
to 1 and possibly reducing the threshold score may solve the problem
without impacting bounce processing for dead addresses.

Mark Sapiro <mark at msapiro.net>        The highway is for gamblers,
San Francisco Bay Area, California    better use your sense - B. Dylan

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