[dba-Tech] Anti-SPAM solutions

Hi All,
'tis that time again - the one where I ask what you all use as an anti-spam
solution.
 
I have recently tested a few applications that integrate with outlook and
outlook express. My testing has confirmed that the solution I have been
using is still at the top as it works quite well but it is one that I really
don't want to use anymore. 
 
Therefore I'm looking for your suggestions. Open source solutions are
welcome.
 
John B