postgrey question

Bill Moran wmoran at
Wed Jun 1 07:22:48 PDT 2005

Bart Silverstrim <bsilver at> wrote:

> I've been looking into ways of improving our spam filtering.  Currently 
> I'm running postfix with amavisd-new (spamassassin and clamav), and saw 
> an article on greylisting using postgrey.  Turns out there's a port for 
> it already in FreeBSD.
> I am still googling for info, but as I understand it the policy will 
> inject the message to another queue for postgrey to evaluate?  If this 
> is true, what happens if I install it while still running the 
> postfix/amavis solution, which is also a double-queue system for 
> evaluation of messages?  Will doing a make install for postgrey damage 
> the installation we currently have in place and working?
> Anyone else running postgrey with amavis on postfix, on FreeBSD?  I'd 
> appreciate any feedback/experiences people have to offer.

Yes, I'm running Postgrey with Amavis on FreeBSD.  Works great.

The short answer is that Postgrey plays nice with Amavis.

The medium-length answer is that Postgrey simply becomes another check
that is run.  Postfix has a "policy service" hook that allows Postfix
to consult with an outside program prior to accepting mail.  This is
a different process than the multi-queue system that Amavis uses, and
the two co-exist nicely.  Postgrey works more like the rbl checks than
the multi-queue system that Amavis uses.

The long answer is contained in the technical details of Postfix, and
the Postfix source code, and I won't attempt to duplicate that here ;)

Bill Moran
Potential Technologies

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