[Mimedefang] Rejecting spam - users unsubscribed from distribution lists

[Joseph Brennan]

Ingeborg Hellemo <Ingeborg.Hellemo at cc.uit.no> wrote:


> The problem we have recently discovered is that some distribution lists
> allows  high scoring spam to be sent out. It then gets rejected by our
> mailserver and  our users get unsubscribed from the lists as if we had
> returned "User unknown".
>
> I'm not very fond of silently dropping high scoring spam on the floor
> since  any "real" senders will not be notified of their message not
> getting through.
>
> How do you handle this?


You must be referring to Listserv.  Its standard message tells people
that all 5xx errors mean "user unknown", that refusing mail for a valid
user must be a system problem, that our mail server is unreliable,
and that the user should consider another service provider.

I send mail to postmaster and list owner.  I ask whether THEIR server
really delivers virus and spam to users, and if not, to stop libelling
our university's IT department for refusing it.  This is cc-d to our
user.  It sometimes gets action.

I feel very strongly that nothing should be dropped.  False positive
is always a possibility however small.

(OK, we do drop mail claiming to be from our own incoming service
addresses like postmaster at columbia.edu, since we know for certain that
no legitimate mail comes from those addresses.)

Joseph Brennan
Columbia University Information Technology