Field guide to spam

[egghead]

FIELD GUIDE TO SPAM.......... Leading anti-spam researchers and members of the Sophos anti-spam task force, authored this compendium of the various types of tricks that spammers use to subvert anti-spam filtering software

http://www.sophos.com/spaminfo/explained/fieldguide.html

source Shell extension city (http://shellcity.net/?egg=b)