Comment spam is a big problem with WordPress blogs. I get much more automated spam comments on this wordpress blog then what I got at Blogger.
Firstly Blogger had introduced the first line comment spam blocking via introducing a captcha, word verification typing to ensure that automated comment spam was blocked easily. You could then moderate all comments before going live.
The default WordPress plugin which come preinstalled with WordPress is Akismet. You need to activate it from the plugins menu after getting a WordPress API key. Sign up for a WordPress.com account. Where is your WordPress API key? Go to Account link on top right corner of your WordPress.com dashboard and you will find it. Don’t share your API key, it’s like a password.
When a new comment, trackback, or pingback comes to your blog it is submitted to the Akismet web service which runs hundreds of tests on the comment and returns a thumbs up or thumbs down. When the plugin catches something as spam it saves it in the database for 15 days in case you want to check it out manually and then automattically deletes it. In the unlikely event something gets incorrectly identified as spam you can correct it and it submits the “false positive” back to Akismet for analysis and improvement of the system.
The Akismet alternative which many bloggers say is equally effective is Spam Karma 2. Spam Karma 2 (SK2) is an anti-spam plugin for the WordPress blogging platform. It is meant to stop all forms of automated Blog spam effortlessly, while remaining as unobtrusive as possible to regular commenters. If you get too many good comments getting blocked, called false positive, you must read why. SK2 requires WP 1.5.1 (and up).
I know many wordpress users use both Spam Karma and Akismet to stop comment spam totally.
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