[Mimedefang] filter by final recipient

Joseph Brennan brennan at columbia.edu
Wed Sep 21 11:43:15 EDT 2005

"Kevin A. McGrail" <kmcgrail at pccc.com> wrote:

> Tired of the SCOMP TOS emails, eh?

Real tired, since the cause is AOL users.  Namely AOL users who
forward their columbia.edu address to AOL.  The options I can come
up with are:

1. Filter mail to AOL more heavily, as in rejecting more legit mail.
This is not only hard to accomplish but will probably result in more
helpdesk calls about mail not being delivered.

2. Find all the forwards to AOL once a month or so and send them all
mail asking them not to hit "report as spam" for forwarded mail.  My
guess is that plenty of them will start hitting "report as spam" when
they get the reminders, and we'll be worse off than when we started.

3. Forbid people to forward to AOL.  This is pretty much what AOL is
telling us by their actions.  This will create more helpdesk calls,
and start chipping away at the alumni forwarding program.

I don't like any of these, so I haven't given a whole lot of time to
figuring out option No. 1.  I guess a variant of No. 1 is to bounce
back everything telling the sender what the AOL address is.

By the way we are unusual I think in that we actually reject spam.
Many universities accept spam and put it into the user's spam folder.
For forwarding I imagine they just forward everything and leave it
to the end system to sort it out.  What does AOL do with them?

> Have you considered simply using procmail rules instead of .forward's?

No, because (a) we're moving to a Cyrus system soon and we'll get rid of
procmail, and (b) probably a lot of it is alumni forwarding which is
done with an aliases file.

However I have considered the hokey method used to make procmail act
like a milter-- not AS a milter, but sort of LIKE a milter.  Make a
procmail mailer, and sendmail outputs to it, it checks, and it forks
another sendmail if the message should be sent.  This stinks because
it starts up extra processes and it doesn't reject during smtp.  This
kind of thing is why milter was created, and I never wanted to think
about it again.

I think filtering by final recipient can't be done in a practical way.
There, if someone takes that as a challenge, good.  By final I mean
by recipient after aliases and .forward files have been applied.

Joe Brennan

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