Testing out Postini and gave them a day to catch up. I've been sending all my spam and full mail headers to email@example.com as recommended on the contact page of their web site. Here are the statistics so far.
Today Postini caught about 33 spam messages.
I sent them about 61 messages that their spam filters did not catch.
That being said I just recently added some spam ridden aliases to their spam configuration (which is pretty decent though it could be a bit more user friendly and easy to find what you are looking for...)
Also I found a bunch of spam -- in my SENT items - which were sent to me on the Intermedia mail system which I think is based on Horde. Some of those may have been pretty old.
As I write this I just logged in to find two more spam messages in my in box.
We'll see how they do tomorrow...