SpamJam

SpamJam is an anti-spam program compatible with almost any POP3...

SpamJam is an anti-spam program compatible with almost any POP3 mail server and client software. SpamJam operates on your PC as a local mail proxy and ensures that spam is never downloaded to your PC.

Filtering rules can utilize both binary logic and probabilistic approach, and can be organized into an hierarchical tree of an arbitrary level of complexity.