For some reason I have gotten a lot of irritating comment spam the last couple of weeks. The comments are all on the form "Good site. Thanks!", tend to hit a few old posts, and somehow manage to slip through Movable Type’s pretty good spam filter. I have tried upping the strictness of the spam filter, but that has resultet in some legitimate comments disappearing into the spam holding pen.
What to do?
Applied Abstractions 
You should try Akismet. Go to “Development” and download the MT-plugin. I’ve written about Akismet over at bloggblogg.
You should try Akismet. Go to “Development” and download the MT-plugin. I’ve written about Akismet over at bloggblogg.