As of today all new registrants willhave to answer a simple question to prove that they are human . . . this should stop any 'bot' signups, which account for the vast majority of spam signups for bulletin boards.
The software notifies me whenever there is a spam signup denied - it has caught four in the first hour and a half of being set up.
Of course it won't stop malicious human signups, but these represent a small minority. The board will be monitored on a daily basis to remove any of these.