pop3 spam filter firewall or hosted service

Hello I am trying to find a services that will retrieve email from a pop3 m
ailbox and have a web interface to manage spam.  I only found 2 options so  
far. I believe the barracuda email firewall has a feature that works like t
his but it is a little expensive for our 15 user setup.  Also I found a web
site that does something similar but it has not been as accurate as I wante
d. It is called  
http://www.bopspam.co.uk/
Does anyone know another way to achieve this goal? Thanks.