Filter missing all trackbacks

Apparently we have a new wrinkle in spamming -- spamming via trackback. Several sites, including mine, are getting spammed by a spammer whose comments already were getting caught. In other words, the same domains and trigger words and the same kinds of posts are not getting caught if the spam comes in via trackback.

Is there a way of having the spam filter evaluate new trackbacks for spam potential? Until then, I'm afraid I will have to disable the module. Others already have.

Help!