Since I have installed amavisd and maia, I find it interesting to see how effective it is. I have installed mailgraph.
This are my current stats
This is a great software where it scans all mail coming into our server for spam and viruses. If it finds a spam or virus, it will quarantine the message and can notify the sender and receipient.
This is some add-on software to amavisd-new, that will quarantine the spam and viruses into a mysql database