As I mentioned recently, this blog is just inundated with spam on a regular basis, and keeping it from making it into comments is quite a chore. The first step in fixing the problem was to install a CAPTCHA system (in our case, we used a simple math question rather than a hard-to-read image), but it doesn’t solve all the problems. For instance, the other source of huge levels of spam was fake trackbacks. Solving this, however, was so simple I should have done it from day one.
The solution was to install a simple WordPress plugin to check for a legitimate link to our blog – it loads the referenced page from each trackback and searches for a link. If there isn’t one, it marks it as spam. Simple – and it’s reduced the number of spam comments that reach our moderation queue to near-zero.
Between the trackback checker and the CAPTCHA, blog spam is much more manageable.