Like a lot of other sites, I started receiving a ton of trackback and comment spam a couple weeks ago. I was set up for all new comments to be moderated, but even that step became a burden. Plus, the trackbacks are not moderated which the spammers have just realized I suppose.
After reading up on the various solutions people have created for MovableType, I installed MT-Blacklist. I was at first reluctant to rely on a blacklist approach, but this plugin is quite powerful, automatically updating its blacklist from the master at Jay’s site. You can also add your own search expressions to fine tune your filtering (hint: add ‘texas’ and ‘poker’ to your list). MT-Blacklist has effectively killed 100% of such spam on my site.