Comment spam | Site management

Comment spam

Comments are a great way for webmasters to build community and readership. Unfortunately, they're often abused by spammers and nogoodniks, many of whom use scripts or other software to generate and post spam. If you've ever received a comment that looked like an advertisement or a random link to an unrelated site, then you've encountered comment spam. Here are some ideas for reducing or preventing comment spam on your website.
Use anti-spam comment tools

Most website development tools, especially blog tools, can require commenters to prove they're a real live human, not a nasty spamming engine. You'll have seen these: Generally the user is presented with a distorted image (often called a CAPTCHA) and asked to type the letters or numbers she sees in the image. Some CAPTCHA systems also support audio CAPTCHAs. This is a pretty effective way of preventing comment spam. The process may reduce the number of casual readers who leave comments on your pages, but it will definitely improve the quality of the comments.
Turn on comment moderation

Comment moderation means that no comments will appear on your site until you manually review and approve them. This means you'll spend more time monitoring your comments, but it can really help to improve the user experience for your visitors. It's particularly worthwhile if you regularly post about controversial subjects, where emotions can become heated. It's generally available as a setting in your blogging software, such as Blogger.
Use "nofollow" tags

Together with Yahoo! and MSN, Google introduced the "nofollow" HTML microformat a few years ago, and the attribute has been widely adopted. Any link with the rel="nofollow" attribute will not be used to calculate PageRank or determine the relevancy of your pages for a user query. (For example, if a spammer includes a link in your comments like this:

This is a nice site!

it will get converted to:

This is a nice site!

This new link will not be taken into account when calculating PageRank. This won't prevent spam, but it will avoid problems with passing PageRank.

By default, many blogging sites (such as Blogger) automatically add this attribute to any posted comments.
Disallow hyperlinks in comments

If you have access to the server, you may want to change its configuration to remove HTML tags from comment links inside your guestbook. Spammers will still be able to leave comments, but they won't be able to publish active hyperlinks.
Block comment pages using robots.txt or META tags

You can use your robots.txt file to block Google's access to certain pages. This won't stop spammers from leaving comments, but it will mean that links in these comments won't negatively impact your site. For example, if comments are stored in the subdirectory guestbook, you could add the following to your robots.txt file:

Disallow:/guestbook/

This will block Google from indexing the contents of guestbook and any subdirectories.

You can also use the META tag to block access to a single selected page, for example http://www.example.com/article/comments. Like this:





Think twice about enabling a guestbook or comments

A lot of spam doesn't give users a good impression of your site. If this feature isn't adding much value to your users, or if you won't have time to regularly monitor your guestbook or comments, consider turning them off. Most blogging software, such as Blogger, will let you turn comments off for individual posts.