OT: Sendmail antispam relay HOWTO

[Timothy Alberts]

On Tue, 2006-10-10 at 09:16 -0700, Brian D. McGrew wrote:
> I want to use FC3 to setup a mail relay/spam filter using sendmail so
> that my Exchange server doesn't talk to the world anymore!  In essence I
> want sendmail to talk to the outside world, run a spam and virus check
> on the incoming mail and then relay it to the Exchange server; and then
> do the same for outbound mail.
> 
> Can someone point me to a FC3/Sendmail HOWTO on getting this done?  It's
> been a while since I've messed with sendmail stuff like this?

I can't point you directly to any tutorials as I'm in the process of
doing something similar, but what I have learned is that sendmail
spam/virus filtering is best done with sendmail's milter (mail filter)
interface.  The standard packages for spam and virus seem to be
spamassassin and clamav.  I will say that spamassassin is awesome, I use
it on my domain email servers.  The latest version 3.1 seems to be
finding spam etc almost perfectly.  However I currently use it with
procmail as the MDA, not as a milter.

I am in the process of integrating clamav and spamassasin using the
milter interface.  However, I've learned that doing this directly is not
recommended by some websites.  In fact the milter interface should use
MIMEDefang which will tie spamassassin and clamav to sendmail.

For details and info, I would start searching for keywords sendmail,
MIMEDefang, spamassassin, and clamav.  You will find tons of articles
and how to's.

I would also add www.technoids.org as a reference.  I've been through
much of their documentation and have learned a few new tips/tricks.

I am curious if you have a need to run Exchange with Sendmail as a
gateway rather than just switching to sendmail.  I guess that's just my
bias showing :)