If you keep received spam email and comment from your website registration form or blog comment, may be you can try this Free Anti Spam program, reCAPTCHA.

anti-spam-recaptcha

The program function is random letters/numbers and you must translate in order to prove your humanness, and not machines. You can use it for all registration process in your website. Of course and your blog comment too.

To using it, first you need to go reCAPTCHA website to register a account & get reCAPTCHA key. reCAPTCHA also have plug-in support for WordPress, Movable Type, Drupal, Joomla, phpBB applications.

Click here to read more and register >>