From Jett Fuel Productions:
Counteragent 2 is an application designed specifically for use with EIMS Server X on Mac OS 10.3.9/10.4.x. Counteragent 2 enables virus filtering by using ClamAV and spam filtering using SpamAssassin. Mail is filtered by Counteragent 2 after it is received by EIMS and before it is delivered to local mailboxes and/or sent out to other servers. Counteragent 2 uses a modified version of the EIMS Interceptor Filter X. When a message is received by EIMS, it is handed off to Counteragent 2. Counteragent 2 then uses ClamAV to scan the email and Counteragent 2 takes action (based upon Counteragent's preferences) when an infected email is found. MIME attachments are automatically decoded/scanned and archives are also expanded, decompressed and scanned. Counteragent 2 automatically checks hourly for updates to the virus definition files and installs them when new versions are available. Mail that has passed the virus scanning phase is then scanned using SpamAssassin. SpamAssassin grades messages based upon their "spamminess". Messages scoring over the configurable "Spam Threshold" are handled as spam. Options for handling spam include: simply adding SpamAssassin headers, rewriting the message subject, or attaching the original message to a spam report. There is also a "Can Spam" threshold that can be specified. Messages scoring above this threshold are not delivered. SpamAssassin automatically learns as email is passed through it and it becomes more and more accurate at identifying spam. It can also be trained manually on messages that should have been marked as spam, and can learn directly from "Spamtrap" addresses.