This document discusses various techniques for preventing spam on websites, including CAPTCHAs, user registration validation, comment moderation, blacklisting IP addresses, and obscuring email addresses. It provides examples of specific Drupal modules that implement anti-spam features like Akismet, Mollom, reCAPTCHA, and IP anonymization. The document also describes how spammers try to circumvent these protections, such as using humans or malware to solve CAPTCHAs, and how more advanced techniques like image recognition CAPTCHAs are still vulnerable to attacks.

1. SPAM Wars Maurice Green, PhD Design 4 Drupal January 24, 2010

2. What is SPAM? (According to Wikipedia)

3. A canned meat product…

4. A “Weird Al” Yankovic song

5. A Monty Python comedy skit

11. Registration SPAM

13. User Registration Page

14. Failed Registration

15. www.stopforumspam.com

17. Confirmation Login

19. CAPTCHA

20. CAPTCHA

21. CAPTCHA

27. Image CAPTCHA

28. Google’s Socially Adjusted CAPTCHA

29. Another Image CAPTCHA

30. 3-Dimensional Image CAPTCHA

31. Humerous Image CAPTCHA

33. Egglue Semantic CAPTCHA

38. Anti-CAPTCHA System

40. Test for Anti-CAPTCHA worker

43. Captchar_A Trojan (2007)

44. Captchar_A Trojan (2007)

45. Drupal Anti-Spam Modules

69. www.projecthoneypot.org