Please upgrade to 2.2 here.
The 2.0 and 2.1 branches are no longer being updated.
I recently noticed an increase in Spam-Bot registration in my forum. They are still not posting, but i'd like to have some kind of prevention for this kind of user registration.
Maybe a captcha or another tool could help.
Cool would also be an option to delete more than one user at once.
What do you think?