Overcoming spam in Drupal website is a work that is sometimes quite time-consuming. Spam also increases caused by the search engines like Google with its PageRank, which makes website owners do variety of ways to get a high PageRank, one of them is by doing a Spam comment on the comment form provided on an article, or creating a spam forum post.
There are many Drupal modules available to stop the Spammers, for example are Captcha or Mollom. Both module blocks robot spam submissions by requiring users to answer a challenge question before posting a comment, or registering etc.
Then how about a backlinks we do not want? to solve this problem you can try NoFollow List module, the module allow you to add a rel="nofollow" tag to all links that come out of your website throughout your article. To do so, simply put your site on the WhiteList in the module settings.
But there is one weakness of NoFollow list module, this module can not add a rel="nofollow" tag into comments in your article. Fortunately it can be overcome by doing the following trick:
- Go to Administer > Input formats.
- Click "configure" under Filtered HTML.
- Click "configure" again under Filtered HTML tab.
- Check the "Spam link deterrent" and "Save configuration".
Now all links that comes out of your website will have a rel="nofollow" tag.