Overview
The
Spam Blocker module checks input from your users to see if it contains spam.
When a new user signs up to your site, you can put them in a probation period where everything they post is run through the spam filters, you can strip all the HTML they post and take action on URL's they post.
This is to deter users from signing up to your site and posting a bunch of spammy comments with links back to their non-related site.