Arresting Spam With CAPTCHA

by Gary on October 29, 2007 · 2 comments

in Website Design

Do you receive lots of spam from your contact from on your web site? Spammers can exploit your contact form script to send tons of spam your way. Sometimes the problem escalates so much that your hosting company threatens to close down your account if you do not take corrective measures to stop spam from your contact from. Many ways can be implemented to stop the spammers but sooner or later they find a way around and resume sending you spam. One of the most prevalent methods of stopping contact form spam is to use CAPTCHA image. It stands for “Completely Automated Public Turing test to tell Computers and Humans Apart”.

CAPTCHA generates a random graphical string of characters or numbers whenever the form is loaded. The person who submits the form also has to enter the information being displayed in the CAPTCHA image. Since the information in the CAPTCHA image is randomly generated it cannot be guessed by the spammers. When the form is submitted the mailing script verifies the CAPTCHA information and if the entered (CAPTCHA) information is incorrect the form is not mailed. You can find more information on the CAPTCHA web site. All major scripting languages these days support the CAPTCHA implementation.

But does CAPTCHA really work? Accessibility is a big problem sometimes with CAPTCHA and some webmasters claim that hard core spammers can overcome the CAPTCHA hurdle too. I haven’t tried it yet. Have you implemented CAPTCHA on your website or your blog? If yes than I would love to hear from you regarding this in the comment section.

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  • Jan from thrusites design

    I integrated the CAPTCHA plug-in into my WP-MU blog because spam bots were creating spammy blogs about 3-4 times a day. It helped me and now I am happy with the result :) .

    However, if you are using your own engine, then there are easier ways how to get rid of spam. For instance, one of my sites would receive about 1000-2000 spam messages a day if I didn’t filter them. Without CATPCHA :) . It works and spam is filtered 100%. My spam filter is based on checking words only, no IP blocking.

  • Gary

    Hi Jan, welcome to Phoenix. Glad to hear that CAPTCHA is working for you.