SpamPal

SpamPal is a free spam filter which works well with VPOP3

SpamPal works as a POP3/SMTP proxy, so you need to reconfigure VPOP3 to download and send mail through SpamPal instead of directly to/from the ISP.

SpamPal supports plugins which allow its functionality to be extended.

Basic SpamPal functionality includes a real-time blacklist processor and IP & email address based blacklist and whitelists.

Some available SpamPal plugins extend the functionality to include Bayesian statistical filters, regular expression checkers for email contents, filter dangerous attachments, filter dangerous HTML, etc.