Linasf is a PHP implementation of a SpamAssassin-like spam filter. It uses Bayesian Filters, User-defined rules and Artificial Neural Networks to obtain excellent results.
Training and integration with current PHP system is very easy. (uses MySQL as DB)
A multiuser spam filter for IMAP servers using a simple statistical method. Training is done within any imap mail client. You simply move the mails into the right folders to train the tool. Can be installed server or client side. Using PHP(imap) + Mysql.