The only thing I really don’t like about MT-Blacklist is that I have to fiddle around and cut and paste URLs and click a lot when I want to mark a comment as spam. This is mostly my own fault for using an old CRT-based mail reader, but still. So I wrote a little script that takes an MovableType comment email as input and runs MT-Blacklist on the comment. Now, whenever I get comment spam, I pipe the email alert to this script and the comment spam goes away.
This works for me. It may not work for you. No warrantee, etc. Test before using. Requires the CPAN modules WWW::Mechanize and HTML::TokeParser.