Spamarrest is, hands down the best money I ever spent on the internet. I originally saw it when I sent an email to thehun and got it a few months later. I have seen something new just like it also. I used to use rules, filters all that crap; spam still got through constantly. The nice thing about spamarrest also is you can add/block entire domains if you wish as well as single addresses. You can upload your address book which allows you to authorize everyone on your list (of course you can remove them/block them also if you like). I am literally 99.9% spam free now that last .01% is due to the occasional person I just don't want to hear from

It uses a Turing test which completely eliminates AI generated email.
http://spamarrest.com/affl?1986305