I use cloudmark, like it except it occasionally filters an email that *I* do not consider spam. But I guess that is the drawback of using this kind of system. The one thing I do not like about cloudmark is that ther is one particular spammer which it will for some reason simply not filter, and yes, I submit it every time.
For the price, I might even check out SpamKiller. But it's said that I have to spend money/gp thru all this in order to get rid of something I did not ask for in the first place.
There is an interesting article on DSLreports.com regarding IBM working on some way to track spammers and make them pay for every email.
Anyway, back to the topic: thanks for the info about SpamKiller.