Do you have activated the Akismet plugin to prevent comment SPAM? of course this is not complete until you install the Captcha on your blog. Captcha plugin popular today and has the best rating is the SI-Captcha. With this plugin, your blog will be protected from the comments made by robots.
for features and provisions of the SI-anti-SPAM Captcha is:
Features:
Configure from Admin panel
JavaScript is not required
Valid HTML
Section 508 and WAI Accessibility Validation.
Allows Trackbacks and Pingbacks
Setting to hide the CAPTCHA from logged in users and or admins
Setting to show the CAPTCHA on the comment form, registration form, login, or all.
I18n language translation support (see FAQ)
Captcha Image Support:
Open-source free PHP CAPTCHA library by http://www.phpcaptcha.org is included
Abstract background with multi colored, angled, and transparent text
Arched lines through text
Generates audible CAPTCHA files in WAV format
Refresh button to reload captcha if you cannot read it
Requirements/Restrictions:
Works with Wordpress 2.6+, WPMU, and BuddyPress
PHP 4.0.6 or above with GD2 library support.
Your theme must have a ID); ?> tag inside your comments.php form. Most themes do. The best place to locate the tag is before the comment textarea, you may want to move it if it is below the comment textarea.
By installing the SI-Captcha, comments are automatically sent frequently performed by software will be minimized.