Stopping Ads SPAM - How do you deal with?

In the last 3 years, Spammer found many different way to bypass spam filters on any vendor. Users receive email from ADS website (newsletter) where they never subscribed for. I can confirm it. I have a mailbox on a customer site and I used it to subscribe on Techtarget, HP newsletter and few other IT newsletter and now....on that mailbox I receive a lot of newsletter from other website. Real Estate, Holiday promotions, Tickets promotions, etc...

So I know that websites share information among them and cookies play another important part of the spam, but how are you guys preventing this sort of SPAM?

The advice is to use the working email only for business usage only and this is regulated by "Acceptable Use Policy" and by blocking certain web categories, but this is not enough as users can access email from home, subscribe from home (they signed the AUP so they should not use it).

I would like to also know how Sophos Labs are classifying those emails (the spam score). On Pure Message there was the spam score level and you can adjust the spam and suspicious spam based on score level but this is not possible on SEA. This is a missing feature I would like to see.

Guys, what is your point of view? Do you have the same issue?

Thanks