SpamBayes: Bayesian anti-spam classifier written in Python.
The Version 1.0 release candidate (both source and Windows binary installer) is now available!
This is another sourceforge program I use daily. The Junk email filter in Outlook 2003 seems to be doing a good job but this catches the rest. I will wait until the stable version is released. All spam programs can detect spam but the good ones avoid false positives.