How to Protect Your Blog’s Comment Form from Spam - dummies

How to Protect Your Blog’s Comment Form from Spam

By Amy Lupold Bair

The tools described here are designed to give spammers trouble filling out the comment form on your blog. These tools try to prevent the spam from ever reaching your blog so that you don’t need to deal with reading and deleting it.

These tools do that job fairly well, but they also present something of a barrier to people who want to leave a legitimate comment; remember, you want to cut down on spam, not real comments! Keep your audience’s needs and abilities in mind when you implement any spam-fighting tools.


A CAPTCHA (an acronym for something really long and boring) is a challenge-response test, meaning it’s a question that your reader must answer correctly in order to post a comment. On a blog, CAPTCHAs are most commonly implemented in such a way that humans can complete them but computers can’t. A CAPTCHA on the Resourceful Mommy contact form requires the would-be commenter to duplicate the letters and numbers shown in an image in order to submit a comment.

Resourceful Mommy
On this blog, Resourceful Mommy, the visual CAPTCHA is designed to let humans leave comments on the contact form while blocking spam scripts.

CAPTCHAs were created to stop spammers from adding comments to blogs by using automated scripts that try to fill out any web form that they find, especially blog comment forms. But spammers are inventive: Some blog comment scripts can now recognize letters and numbers in an image, so many sites that use CAPTCHAs distort the text by stretching it, or layering it with graphic random graphic elements.

Many readers (and fellow bloggers!) find CAPTCHA gateways to comments to be annoying and aggravating. Although this is a great line of defense against spam, you may not want it to be your first one.

Other sites use CAPTCHA questions that are simple for humans to answer, such as trivia or mathematical questions. For example, “What color is a red balloon?” These kinds of CAPTCHAs are an updated version of the original CAPTCHAs and have become a fairly popular tool for bloggers.

Your blog software may have CAPTCHA technology built in, or you might be able to add one by using a plug-in. Check your blog software’s documentation and support tools for suggestions on installing and configuring a CAPTCHA system.

User registration

Registration is a popular option with larger communities, especially online forums. The community requests or even requires that users who want to leave comments sign up for a user account. These accounts are typically free, but to complete the registration process, you must provide a name and valid email address, thereby cutting down on the number of spam scripts that can create an account and therefore post comments.

Sites that require registration actually prevent anyone who isn’t registered from leaving a comment; sites that simply request registration reward registering by recognizing members or by marking a registered user’s comments in some highlighted way.

This setup lets you keep a record of everything that a particular poster adds to the system, easily identifying your most frequent contributors and visitors. Also, if a poster gets out of hand, or an automated spam system acquires an account and posts by using that username, you can simply close the account and stop the poster from posting again by using that account.

Blog software is increasingly offering registration, so be sure to check your documentation. If your software doesn’t offer registration, look for a plug-in that does.