The ability to stop spam is a problem, as a forum myself and a friend run has grown and become more popular over the years, so has the problem of spam to the point where it gets out of control. However an effective method does exist for vBulletin powered forums, best of all its a free plugin.
We had already taken several steps to stop spam, including:
When a user signs up there name, email and ip address are checked with the database on http://www.stopforumspam.com, if any of the details are in that database the users registration on the forum is denied.
During the registration process the user is also required to enter a reCaptcha and answer a question such as “what would you put in a toaster?” It was believed this would be effective in stopping spam as any bot registering would most likely not be able to answer the question or complete the reCaptcha.
Despite those measures every few hours the forum would be hit with a wave a spam which will be continually posted until the user account is banned.
Example of this:
Even after a user has been banned that user could be seen on the active users list trying to create a new post, despite the user been banned for several months. It soon became apparent a person was likely registering accounts then using a bot to post spam after the registration had been completed and validated.
Over the months we tried a couple of additional methods to stop spam which were really no use at all, however we then discovered the Keyword weight based spam detector for vBulletin.
This product scans any new posts from members who have less than 5 posts (can be changed to save cpu usage) it will look for user defined keywords, such as “hotfile.com”. Every time someone types a banned word in their post that word counts as one point, when that post hits a certain number of points it will be denied.
As all the warez / spam that get posted on our forum appears to be hosted hotfile.com, the word “hotfile.com” is now worth one point. The limit for denying a post is set to one point so any post on the forum with the word “hotfile.com” is now rejected.
This has been pretty much been the end of our spam problems as the bots posting on our forum never appear to post anything apart from warez hosted on hotfile.com. If required in the future we could block other types of spam too.