As far as I can see there is no way to log a contributor as a spammer.
This exists for comments and there are plenty of plug-ins for comments too.
I have somebody (probably a bot) that posts several messages every day.
They don't get published but it's a pain having to delete them.
I use SABRE to ask a mathematical question but this one bot gets through.
Any ideas on what to do would be much appreciated.
Jane