On this very forum I was recommended a what has turned out to be a real spam catcher. However, I was dismayed when I got it because it requires a bit of time to enter the addys of those you wish to exclude. But do it and you see them off for good.
As they come in I
immediately enter their address into the blacklist and they just don't come back.
I love it, it is free and it works.
Her ya go:
http://www.spampal.org.uk/