postfix mail filtering with amavisd-milter - works!

[Jo Rhett]

So I've been a sendmail admin for 20+ years and never saw any need for postfix. I was very happy with sendmail and amavisd-milter and amavisd. However, when rebuilding my colo box I decided to go ahead and learn postfix, just so I can see how the other half lives ;-)

First, I found that all of the published recipes for spam containment with postfix are bogus. They either create back-scatter, or they drop messages which hit the filter instead of rejecting them in the SMTP session like they are supposed to. So if something is a false positive, the far side will never know it happened. Neither of these situations is playing fair to other parties.

So I've done some testing and work, and I currently have postfix using amavisd-milter as a before-queue spam test, which properly rejects spam during the SMTP session. This solves both of the previous problems and brings postfix users closer to being a proper mail gateway. I believe very strongly that this recipe should replace the existing documentation, to avoid sending new users out to become backscatters.

I'm still working out a few details: namely, how to get the permissions right on the amavisd-milter socket. As soon as that is sorted I'll provide documentation. 
Hint: there's no mystery here. I installed amavisd-milter as documented and pointed postfix at it :-)

-- 
Jo Rhett
Net Consonance : net philanthropy to improve open source and internet projects.