Checks where visitors come from and gives them a warning if they are likely to be comment spammers. For DoFollow and exDoFollow blogs.
The default set of triggers have been chosen to be as 'wide' as possible, catching as many potential comment spammers as possible.
One side effect of this is that there may be some false positives. In trialling the plugin, I have encountered almost no false positives, but the possibility exists. It is therefore not recommended to redirect users immediately. The default warning message acknowledges that false positives are possible and asks the user's indulgence in reading the comment policy.
To limit false positives, the comment warning (or redirection) will not trigger for terms that are in both the refering URL and in your page's URL. If you have a post with dofollow in the URL and a visitor arrives from another site with dofollow in the URL, there is a decent chance that they are not a spammer.