What's Up With The Messages?

It's been happening a lot lately... I've been seeing posts on my tagboard on this blog with rather unrelated or sometimes even obscene themes. I've been deleting the messages but I still seem to get these types of posts on my tagboard more frequently now and it is getting very annoying having to go to cbox and delete these messages manually. I wonder if cbox has a spam post filter that I could use to eliminate the messages, much like spam filters on regular e-mail....