Spam Filter Efficiency

[Mitchell Smith]

Greetings List,

I apologize if this topic has already been raised, however I would like some feedback on how people are managing spam in high volume email environments.

To give you a little background, our organization currently has three reasonably powerful boxes (dual XEON with 4GB ram), processing about 800000 messages
a day (total) and are seriously struggling under the load.

Our configuration consists of Postfix with a couple of RBL checks, GLD greylisting (central MySQL db), which falls through to MailScanner which filters
with SpamAssassin / Clamav.

>From the mail scanners, the emails are the forwarded (via an LDAP lookup) to a specific Cyrus mail store.

We have turned off DCC checks in SpamAssassin which has improved performance quite a bit, however we are still doing Razor checks.

We have investigated a couple of commercial solutions which clamed to be able to handle more than our quantity of mail on one box, however the spectacular
pricetags associated with such solutions suggest we won't be moving forward with these any time soon.

We are also looking at other open source solutions such as amavis / dspam to see if we can try and improve the throughput on our current hardware.

What I would like some feedback on is if anyone has already gone down this path and found one solution that performs better than another, or if anyone is
using a similar setup to ours and has found better ways to optimise it.

I would very much appreciate some feedback either on or off list please, as to how other people might be tackling this same problem.

Cheers