I came across a couple of programs, one looks promising and the other I haven't checked out yet.
http://popfile.sourceforge.net - Not as friendly as mailwasher, but it looks like a great way of preventing getting more spam or noticing your getting more
.
The other one is called Tagged Message Delivery Agent, I haven't search for their website, but from what I have read it is installed on the mail server itself and acts as a whitelist/blacklist gateway. I have my doubts about this one.