In a recent blog entry, I wrote about a neat little tool for anti-spam, Spam Shredder. A comment (thanks Andy) to that post recommended POP File, a free tool that does the same thing. I've now downloaded POPFILE, and it's cool. Like Spam Shredder, it's essentially a service that acts as a POP3 proxy. It uses a Bayes engine to identify and tag posts as spam or other things.
POPFile has a couple of neat features. First, it allows you to train the engine to recognise not only spam, but any traffic and place the mails into a 'bucket'. Each bucket allows you to specify whether to modify the subject header (adding [bucket-name] to the header), or to add extra header fields when the mail is passed from POPFile to your mail client. Based on these actions, you can then use your mail client to filter the traffic into folders. I've created three buckets (WORK, PERSONAL and GOOGLE) for stuff I want, and a two further buckets (SPAM and DNs) for real spam and those delivery bounces that are usually spam.
Unlike Spam Shredder, PopFile only supports one mail server. Bur all in all, I find it a nice product. Since installation, it's accuracy has stedily grown - it's currently around 90% after 2 days of training.