I hate SPAM!!! I use to run three website-forums and would spend way too much time blocking, banning Spammers, I would have to manually add the Spam IP, Email Address and Username (three step process) adding them to the Ban-List!! Eventually I ended up closing down two of my websites and got the third one upgraded to the best software forum that has the most advance security and anti-spam feature! NO MORE SPAM!! Sure I still see Spammer's trying to register but NO!!! They automatically get the BOOT!!!
Some spammers are very sneaky, underhanded slime bags!!! They could use hijacked IP numbers or a Proxy IP - - - for example: a Proxy Whois search could reveal that a Spammer appears at first to be from the US but in fact is from Asia.
The bulk of the SPAM posted on forums, Blogs and such are from SPAM-BOTS!!! Unfortunately Spam will keep coming back with another random IP, Email and Username.. unless....
There 'may' be third party add-ons available that will control Spam on this forum! Alternatively there may be an upgrade for this forum software (AspPlayground.net) with Anti-Spam Captcha GD2 which is more advanced!. Also... I've seen random maths questions used as part of newbies registration process now used on phpBB forum software. On other sites members have to also input a code before each post.