SpamAssassin is an open source solution that lots of server admins use to filter incoming email. It looks at the content of email, then assigns scores based on certain criteria. Once the email goes past a certain threshold (set by the server admin), the email is blocked as spam.

Ever wonder what SpamAssassin actually looks for? Below is a link to their criteria, and their corresponding scores. Keep in mind you have no idea what your recipients’ email servers’ thresholds are set to, but it’s neat seeing what ‘spammy scores’ certain items get. Some of our favs:

• Talks about Oprah with exclamation!
• Something is emphatically guaranteed
• Domain name has a .Biz in it
• Contains "Prestigious, non-accredited universities"
• Coded with FrontPage

http://spamassassin.apache.org/tests_3_0_x.html

Interesting stuff, because we’ve seen legitimate emails get a good deal of "spamassassin points" for containing some of their criteria.