I have used trend-micro for 8 months and blocked over 100,000 spam e-mails. Not only does it block spam it lets you set up properties to perform many other functions. Such as monitor certain e-mail accounts, block certain people from sending an individual or the entire system e-mail, monitor if a certain word is used etc... it is amazing. (A tip: I started by entering each domain of e-mail that came in, time consuming to say the least, when I created a blocking profile with words like unsubscribe, remove from list, don't send me this anymore, I blocked thousands without all the work)