When I recently wrote a post which pointed to an article that described a few things you should do with your WordPress blog immediately after having it installed, I noticed Collin made a comment in that, WordPress was like the Windows OS where as, it comes bundled with Internet Explorer for a browser while WordPress comes bundled with (albeit fantastic) Akismet for a comment spam blocker.
With that in mind, here are 9 plugins that you can use either as stand alone replacements or in various combinations to combat comment spam. Not all plugins work nicely with others so be sure to read the installation manual if you decide to use any of these plugins on your own blog.
1. Comments For Cookies - This plugin adds a stylesheet to your blog’s html source code. When a browser loads that stylesheet a cookie is dropped. If that user then leaves a comment the cookie is checked. If it doesn’t exist the comment is marked as spam.
2. Bad Behavior - Bad Behavior is an awesome comment spam blocking plugin. If you can imagine, Bad Behavior is like Akismet on steroids. BH is a plugin which contains a series of scripts which block comment spam, trackback spam, guestbook spam, wiki spam, and even protects your site from some malicious website hacking. It’s been rumored that Akismet combined with Bad Behavior is the ultimate anti spam configuration in WordPress.
3. WP-SpamFree - SpamFree takes a somewhat different approach at combating spam by using a combination of JavaScript and cookies. According to the plugin author, most automated bots are stopped dead in their tracks by using this method while normal web site visitors are unaffected. However, the plugin author does state that there may be a few visitors who have JS and cookies disabled who might be annoyed by this plugin but that those people would be far fewer than the 100% of people which would be annoyed by CAPTCHA’s, challenge questions and other validation methods.
4. Spam Karma 2 - SK2 is the successor to SpamKarma. SpamKarma2 developed in 2007 is a an anti spam plugin which contains a wide assortment of options with the ability to find tune it’s effectiveness. SK2 even comes with it’s own module system where you can download separate modules and add functionality to the original plugin if the default is not enough for you. Despite this plugins age, WordPressers are still chanting about how well this plugin works.
5. Comment Inbox - Developed by Mark Jaquith, Comment Inbox gives you the ease of the moderation queue with the freedom of unmoderated comments. Comment Inbox works by placing all comments except caught spam into moderation which is renamed to Comment Inbox. All comments in the Comment Inbox will show up immediately on your blog so conversations don’t become interrupted by moderation time lines. An effective way of dealing with both spam and bacn on your blog.
6. CAPTCHA-Godfather - This plugin offers four different methods of protectio. The first is a verification code which is always generated dynamically. The second is that each verification code is given a session id which is different from the PHPSESSID value. The third protection is that every session id and verification code gets their own time stamp. The time stamp works on the premise that humans need a few seconds or minutes to post a comment. The last protection involved IP addresses. The visitor’s IP is stored with the verification code and only when the comment contains the original IP it’s then saved and held for moderation.
7. Defensio Anti-Spam - This plugin is used by a number of WordPress bloggers. It works similarly in the same way as Akismet as it is an advanced, spam filtering service that learns and adapts to your behaviors and those of your readers. Defensio also includes support for OpenID, detailed statistics and more. With all of this functionality under the hood, it’s no wonder that this is one of the most popular anti spam plugins in use today, outside of Akismet.
8. Worst Offenders - Worst Offenders is a plugin that you can use to help decrease the amount of time you spend looking through messages to determine if they are spam or not. Worst Offenders analyzies messages already marked as spam and then uses several techniques to identify messages with common sources, subjects, and content. The messages marked as Worst Offenders can then be deleted all at once, leaving only a handful of messages to sift through.
9. WP Captcha-Free - WP Captcha-Free blocks automated comment spam without resorting to CAPTCHAs. It does so by validating a hash based on time (and some other parameters) using AJAX when the form is posted. Comments posted via automated means will not have a hash or will have an expired hash and will be rejected. Unlike using a captcha, this does not place any burden on the commenter.
10. Akismet - There is no way in which I am going to write about spam blocking plugins and not include Akismet. Current versions of WordPress come with Akismet installed by default. Akismet uses a unique algorithm combined with a community-created database to “learn” which comments are comment spam and which are legitimate.
The default configuration for Akismet may not be enough for some. In my own experience, I’ve noticed that by check marking the configuration option to allow Akismet to automatically discard spam comments on posts that are older than a month has dramatically lowered the amount of spam in my moderation queue.
As for myself, I am perfectly content with the performance I have received out of Akismet. However, I must note that some of the success tied into Akismet deals with the way I have configured commenting in general on my own personal blog. For example, for a comment to appear on my blog, a user must fill out the name and email text fields. They must also contain a previously approved comment. I have also configured my comment moderation settings to place comments in the moderation queue if they contain two or more links.
Everyone’s comment spam/configuration circumstances are different, so be sure to experiment with different options or techniques to figure out which comment spam blocking recipe works for you. If you would like even more information on how to combat comment spam, check out this article on the Codex.
Mark Ghosh 
It was wonderful to finally meet a whole bunch of people. I have all the pictures that I took (I should have taken the D70) on my Flickr account with the agreed upon WordCampDallas2008 tag. If you have any questions, have any media from the event that you would like to share or have any questions for any of the events/presenters, please let us know.
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