I am deleting hundreds of spam accounts each day
Out of 200 new user accounts, 1 or 2 are not spammers.
Mollom and CAPTCHA are installed on Drupal 6.x
About 5% look like typical spam accounts with spam profiles set up by humans. Spam content is blocked by Mollom. 95% of the spam accounts look like spambot accounts.
Spambot accounts have randomized usernames like these
About 70% of the spambot accounts are never accessed which means they can't be used to add content to Listology and therefore never trigger Mollom.
None of the spambot accounts post spam profiles or spam content. I assume Mollom is blocking spambot content but I am not convinced the spambots are even making an effort to post spam content.
Which raises the question about strange behavior:
Why would anyone register thousands of spambot accounts over a period of months for no apparent benefit? Is it just to be obnoxious?
I am considering Captcha Riddler to see if it would help.
Suggestions are welcome.