We are using Declude and Message Sniffer since a decade without any problems. Declude ist quite flexible. You can add rules and filters as many as you like. Message Sniffer is the perfect add-on for Declude and the pricing is fair.

I cannot speak as to what is the best solution, but I can tell you that Cyren was a waste of our money. It is a poor attempt at catching spam at best.

 

Joe