did anyone tried a challenge/response email spam blocking...

Hello,

I’d like to know if anyone tried to install a challenge/response email spam blocking system, like Boxtrapper from cpanel, or other.
I have found this one: http://tmda.net/challengeresponse.html and thinking about installing, but I don’t know Unix at all (I know I know: what I’m doing here…?).

Thx.
Marius