Spam Comments are always a problem for bloggers. I also faced this problem and the biggest problem come from auto comment posting. You may get hundreds of spam comments per day, and you may spend a lot of time to manage them. These days there are many software which can auto submit a comment to WordPress based blogs. Getting rid of them is quite a difficult task.
To prevent your WordPress based blog from spam comments, many great free plug-ins are available. These plugins can deduct spam comments and can move them to spam comments or can delete spam from those comments. I am listing some very powerful and useful anti-spam comment WordPress plugins which can protect our blog from the problem of spam comment.
Stop Spam Comments on WordPress with Anti-Spam Plugins
Akismet is one of the most powerful and popular anti-spam comment plugin for your WordPress blog. Each of the submitted comments is checked through its web service known as the Akismet web service. It then informs you regarding the spam comments which you can remove from the admin screen itself. Akismet also furnishes you with Spam reports. It is easy to use too.
WP-reCAPTCHA provides you spam protection for your WordPress blog by utilizing reCAPTCHA anti-spam technique. You can protect the comment section, registration and even the e-mail subscription from spam by using this powerful anti-spam plugin WP-reCAPCHA. It provides one of the most widely used CAPTCHA systems. It is already being used by popular sites such as Facebook and Twitter. WP-reCAPTCHA also incorporates the facility of generating a new CAPTCHA challenge, if the user finds it difficult to read the CAPCHA.
Stop automated spambots by using Growmap Anti Spambot Plugin in your WordPress blog or site. It adds a checkbox in the comment form which users are required to check to confirm that the comment is not a spam. It is checked that the checkbox has been clicked or not. A ticked (checked) checkbox confirms that the comment has been submitted by a real user, and that is not a spam.
Spam Free WordPress is a powerful anti-spam comment plugin. It is equipped to handle any volume of comment spam on the highly visited blogs. This plugin has been developed by Todd Lahman and blocks every automated spam and generates zero false positives. It is one of the easiest anti-spam comment plugin. Spam Free WordPress provides an option to delete the spam comments automatically and comes with many other features too.
Bad Behavior is a PHP-based anti-spam comments WordPress plugin. It prevents the link spam and junk files to be delivered to your blog, forum or CMS. It also blocks the robots which deliver such link spam. It even prevents the spammers from reading your site. Bad Behavior prevents the spam attacks by analyzing the software used by a spammer and as well as the delivery method. It can be used in conjunction with the existing anti-spam services. Bad Behavior can be used with WordPress and lots of other packages, as well.