Recently we have made a few changes to make 2S more secure from spam bots.
In a normal install SMF offers e-mail verification, CAPTCHA and user-assignable security questions. We have increased the CAPTCHA difficulty (from none to a basic pattern) and we have added several new security questions which should confuse bots. The answers for these questions should still be available on the first page of a Google search for anyone not knowing the answers.
We have also made two additions to the site. Both of these use external services to try and track spammers and bots throughout the internet. Between them they should stop virtually all spammers. We might even be able to reduce our security question complexity if these mods work as effectively as they have in the past.
-2S Admin Team