While we're working on a moderation solution for the spam on the list, the problem seems to be getting worse.
As a temporary solution we have disabled discussion thread creation for new users.
As of now all new users who have not been approved by a moderator cannot start new discussion threads. New users can still comment/respond to existing threads, and those comments will go into the moderation queue until that user has been approved.
This should stop the spam for now. The new solution we're working on will create a moderation queue for all new threads, but for now creating a new thread has been disabled for newly registered users.
If you are a newly registered user and are not being approved fast enough please use the contact form to let us know.
Sorry for the inconvenience, we hope to have this resolved soon.