I've done this a few times and it works really well. I use Linux,
Postfix,
SpamAssassin, ClamAV, and a super lightweight cut down version of the
now-dead
Amavisd-lite.

I use this system as an inbound email relay on, or outside, the
corporate
firewall boundary and put Exchange inside. That way if the relay system
comes under attack Exchange still works correctly inside the firewall. I
configure the firewall to only allow my outside email relay to send
inbound
traffic to the Exchange server.

In order to avoid accepting email for users I don't have I've got a
script
that reaches into the Active Directory through LDAP and gets a list of
legal
email recipients every day. I found the script on the net somewhere but
I had to tweak the output a little to make Postfix happy.

Jeff Moss

=20

-----Original Message-----
From: Henry Kwan [mailto:spam@designmedia.com]=20
Sent: Wednesday, April 09, 2008 2:24 PM
To: users@spamassassin.apache.org
Subject: Configuring SA as frontend to Exchange


Hi,

Have been running SA on CentOS for a few years now and everything has
been
working great. But the powers that be want to move to Exchange so I am
trying
to plan a SA frontend that feeds the Exchange server.

As I was thinking over how SA works now and how it might work in the my
future
setup, I was wondering how you would feed unmarked spam to the SA
frontend?=20
Since email is passed through to Exchange, it isn't stored on the SA
server
anymore like it is now. Or would I be limited to just having SA
autolearn?

Also, if anyone has some good links to setting up a SA frontend to
Exchange,
that would be much appreciated.

Thanks!