anti Spam email scanner client similar to spamtitan or spamexpert

We need an email scanner which should use latest technology upto windows 7 and work irrespective of which email client I use. It should be very light and not interfere with the other similar products. So even if I have avg email scanner on my pc, this program should also be able to scan for emails. Please explain how do you intend to implement this program, which technology you would use and do yo see any issues?