The buzz in the industry is about the new Bayesian spam killers. They seem to be more accurate and less prone to mistakes.
There is free open source project known as SpamBayes (click here) that has filters for Outlook and POP3. A commercial version of SpamBayes, called InBoxer (click here) is easier to install and comes with more features and technical support.
I found with Mail Washer that although you were'nt downloading spam onto your computer you still had to read through the addresses and headings to delete the ones you didnt want coming into Outlook Express. I got to the point where I was receiving over 200 spams a weeks. I did'nt bounce my deletions just blacklisted them. Not that it made any difference.
Tiscali my ISP have introduced Secure Mail £4.99 per annum. I uninstalled Mail Washer and installed Secure Mail and it's done the trick. I'm down to about two spam a day. Vast improvement.