Blacklists and Comment Spam

As I’ve mentioned before, I run the excellent Akismet plugin on this site to filter out comment spam. It’s pretty well trained now, so that it’s very rare that a spam gets through to the moderation queue for comments or that a genuine comment gets filtered into the Akismet folder. The site gets dozens of spam comments each day and although I can be pretty certain of the filtering, I still give the Akismet pages a quick scan just in case there are any false positives.

Wordpress itself has a built-in blacklist system that allows you to let the system delete comments automatically if they contain one of those blacklist words. But, this happens after Akismet filtering in the grand scheme of things. The result is that some of those daily dozens that should be automatically deleted are not because Akismet catches them first. What would be useful is if there were a way to change the priority so that the blacklist deletions are done before Akismet is run.

So as an experiment, I disabled Akismet and let the blacklist take care of itself for a few hours. You can edit your Wordpress blacklist via Admin, Options, Discussion. At the bottom of that page, paste or type a single spam word per line and save. There are lots of bloggers who publish their blacklists online: Simple Thoughts, Weblog Tools Collection, there are others. You could merge them into your own blacklist.

Interestingly, if you enable Akismet once again you will find that somehow it has actually captured other spams in the meantime. I don’t know if this is some kind of bug or not, but I saw no false positives in the list after re-enabling. Ideally, it would be best to simply have blacklist run first and then anything that sneaked through to be filtered by Akismet. How that’s done. I don’t know. Any ideas?