While Akismet has done (and is doing) a stellar job at catching comment spam (of which there is far more than one might expect — I would estimate that Akismet is now catching a few hundred spam-comments on this site every few days), it doesn’t extend to catching trackback spam.
Trackback spam seems to be a fairly new thing — I’ve only noticed it on my own site in the past week or so, and it was getting progressively worse, so I temporarily turned Trackbacks off until I find a solution.
If this makes little sense, here’s Trackbacks, and Trackback spam, in a nutshell. A Trackback is basically a feature of many blogs which allow one to “link back” to a post on a different blog. For example, if Brian Glass or mr. Ben happen to have said something particularly interesting, I might comment on it here, and include a trackback link which would “notify” their sites that someone had linked to it. If their blogs have trackbacking activated, often a comment will appear under that specific blog-post — not a comment so much as a link that says, in effect, “Someone else wrote about this post on their own blog, here,” and there would be a link back to the post which I had made. Make sense so far?
What trackback spam is, is some other blog or website sending a trackback notification to your own blog, so that the link to their site will appear on your page; there is generally little or no text in a trackback, so often times keywords are used in the name that is being linked back to. For what nefarious purpose would someone do this? Since the trackback is unlikely to appear on the main page of your site, the only real reason I can see would be to generate “Google juice” — that is, the next time your site is crawled by a search-engine bot, the bot will eventually crawl to the various permalink pages, and will eventually count the link(s) back to the spammers site, thus possibly raising the sites ranking in various sorts of search indexes. If someone knows of other reasons, or wishes to correct my hypothesis here, please comment.
At any rate, it is an annoying and despicable practice. So far, as I mentioned, I dealt with it by simply turning trackbacks off, but I would prefer to allow legitimate trackbacks to work… so I may need to investigate the various plugins which seem to (already) be floating around to address this.
