Spam Filtering in MovableType 3.2

People seemed to jump off the MovableType bandwagon when the comment spam started getting out of hand. Having stuck with MovableType myself, I’ve come to discover the new spam filtering power that is currently available.

Bundled with a standard install of MT are three plugins under the SpamLookup umbrella: Lookups, Link, and Keyword Filter. The settings can be configured for all blogs or tweaked for each blog individually (What’s that, you actually write a blog about Viagra and Casinos?).

For the various options, you can push comments to moderation or to junk them entirely. When junked, you can determine how long items should remain in the system before being deleted entirely. Junk settings can only be set on a per blog basis and are available under Settings > Feedback. You can set the threshold for which a comment is considered junk which I haven’t changed. I just modify the weighting on other factors which I’ll get to. By default, auto-deletion of junk is turned off. I’d recommend turning it on. No sense letting hundreds to thousands of junk comments collect in your database for nothing. Then specify the number of days you feel comfortable storing. I’d still recommend a few days because it’s always good to take a peek from time to time to see if any legitimate comments get caught (for me, that’s about 1 in a 1000).

At the core of all three plugins is a weighting system that allows you to give a higher or lower weight to various factors. If it’s below a threshold, it’s junk. If all looks good, it goes live. Beside various options is a link called “Adjust scoring” that when clicked will display a box allowing the weight to be increased or decreased. Scoring is only adjustable on junk settings. If you set a feature to moderate then it’ll moderate right away.

Lookups

Lookups allows you to specify IP and Domain Name lookup servers. Often comment spam pours in from addresses known to be used by spammers. Sometimes legitimate commenters have their IP address on the blacklists. In this case, other weightings should hopefully put them in the clear. You can also specify specific IP or Domain Names to appear on the whitelist. The default settings for this plugin have worked dandy for me.

Link

Link limits the number of links that people can have in their comments. Since spammers tend to be link happy, this manages to catch quite a few of them. Keep in mind that the URL field is also included in the count. That means that a URL plus two links in the comments will hit the moderation default of 3 links and throw the comment into moderation.

The Link Memory and Email Memory is a handy way of rewarding repeat commenters and saves you from having to constantly moderate comments. However, the default weight of 1 is a little low. I’ve bumped it up to 2 to minimize the need for moderation on what are likely legitimate users. If you don’t publish email addresses publicly (which I don’t believe you should) then you could even bump up the score on the email memory.

Keyword Filter

Keyword filtering is likely the one you’d need to update from time to time as you find yourself being inundated with certain comments. For example, I had been seeing an inordinate amount of Viagra spam of late. So I added the keyword to my junk list. What’s handy about this plugin is that you can use regular expressions or even specify a score for certain words.

Tweaking

It’s always good to check your junk comments from time to time to make sure that comments are inadvertently getting caught and if you find yourself with a large batch of spam getting through, it should be easy enough to tweak the settings to capture what you don’t want. The junk comments are accessible via the tab on the main comments screen.

Here’s to a life without spam!