I have been having a serious problem with spam of late. Practically every day this week I have had to delete comment and trackback spam. And not just a couple. Some days it was in the hundreds even with MT Blacklist. It got so bad it was causing server issues.
So I decided to take desperate measures. I have removed the trackback capability on this blog. I did the same thing on my personal blog where things were worse. I hope this solves the problem.
We now return to our regular programming . . .
I had the same problem on a MT blog using Blacklist. What fixed it was a captcha (where the commenter has to enter numbers/letters to prove they are human). There was one James Seng developed that even *I* got working. http://james.seng.cc/archives/000145.html
I had to modify blacklist too though, but my comments problem cleared up like that. (I’ve since become a WordPress person).