Thank you for the replies.

I've tried creating my own filters but I found it was too time consuming and not good enough. The main problem is that I use Outlook to check my POP mail from three different computers as well as my ISP's web mail interface. It becomes too much work to duplicate my filters everywhere.

The Bayesian filters sound really cool and I can believe that they are effective. POPFile looks like it would be awesome if I only checked mail from one location. But again, I'm using 3 computers plus web mail.

I think what I need is something that cleans up my POP account instead of operating only on what has been downloaded. The filtering service at http://spamcop.net looks interesting. Anyone used it? I'm a cheap bastard but $30/year is worth it if it's effective and doesn't require much effort on my part.

-Dylan