I haven’t posted an article about another persons plugin before, but every now and then, one impresses me enough to want to pass along to others. This plugin, Cookies for Comments, is one of those plugins.

Installation

One of the easiest ways to install this plugin is to go to the “Plugins” section of the dashboard, go to “Add New” and search for “Cookies For Comments”.
Use the auto installer.
Once installed activate the plugin from the link on screen.

Next in the “Settings” section of the dashboard, under (you guessed it) “Cookies For Comments”, you can set the system to either mark as spam or delete comments that do not contain the cookie.

That’s about as complicated as this plugin gets :)

Advanced Configuration

Cookies For Comments also has a .htaccess option in case you do not want these comments even reaching WordPress. With this in place it means that the spam comments shouldn’t hit the wp-comments.php script or the database (so you don’t have to delete them manually) if the cookie is not present:

    RewriteCond %{HTTP_COOKIE} !^.*XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX.*$
    RewriteRule ^wp-comments-post.php - [F,L]

One last thing..

One thing I did notice about this plugin was that after activating, and using the recommended image option in the settings a white band had appeared at the bottom of the page (where the image and cookie is placed in the HTML). Now I’m not sure how many people have experienced this issue, but just incase you do, this is how I hid the white space with CSS (display: none; would also work).

img[alt="css.php"] {
    position: absolute;
    margin: -1px;
}

Of course when all is said and done, some comments may still slip through the net, and as always its a constant evolution of a problem.
I will be trying some other plugins out for spam control and see how this site fairs and report back in a future post.

Plugin Page : http://wordpress.org/plugins/cookies-for-comments/