Proofpoint spam protection

I was talking with Tango the other day and he was amazed at the amount of spam I get. He's been my mail server for a while now and because he works at Proofpoint, he runs all my mail through it to filter spam. I didn't run any exact numbers, but I am estimating that I get around 800 emails a day of which about 85% are marked correctly as spam, and maybe another %10-15 are false negatives and less than %5 are true legitimate emails. Tango says their product is good and I'm the exception rather than the rule. They do much much better on everyone else's mailbox he says.

There are two things that make my mailbox a bit more complex than the average mail user, but because proofpoint is an enterprise product, I would think it would deal well with them. First, my email address is old, more than 8 years old, and I've never changed it. Second, I have a blind forward from all of chen.net. Which means that if you send email to a Random.User.Name at chen.net I will get it, unless it's to one of the couple dozen people I specifically forward email. But that shouldn't be too unusual either.

Proofpoint still works well, but I have no idea why it can't identify some things that I get which are obviously spam.

I might install Spam Assassin as a backup at some point.