I've been using SpamCop to filter spam for several months now. Initially, I relied on the many blacklists that they use, but recently switched to implicitly blocking all mail, and explicitly allowing only mail from legit addresses/domains. This worked very well, aside from the minor inconvenience of having to add addresses to my whitelist from time to time. Recently, I've been getting more and more spam with my own email address in the from field, which means it is making it through as my domain is on my whitelist. It's time to look for another solution.

I've tried Spam Assassin, but didn't like it enough to shell out $30 for it. Today, I came across a review of CloudMark SpamNet. Visit their site to read up on their unique approach to fighting spam. After I've used it for a bit I will post a review.