Comments closed but still spam!

Did you try spam karma? that may help.

I am also getting spam in my comments on posts where the comments are closed. (I’m using Autoclose Comments plugin by Scott Hanson)

It doesn’t seem like it should be possible to post any comment, spam or otherwise when the comments are closed. I’ve gone to the specific posts and verified that I cannot post a comment.

Probably trackback spam…. what spam plugins are you using?

You might try Angsuman’s Referrer Bouncer – https://blog.taragana.com/index.php/archive/word-press-1-5-plugin-referer-bouncer/ if it is trackback spam.