BlockAnonymousLinks is a simple module which blocks comments from anonymous users that contain links.
It relies on the fact that most spam messages contain hyperlinks and also on the fact that (for now) (most) spambots don't register on the sites they want to spam. It tries to block comment-spam at an early stage.
If an anonymous user tries to post a comment which contains a link, he/she will get a message explaining why the comment has been blocked.
This comes out handy when you want to allow anonymous comments on your site and you want to prevent most of the spam messages from being submitted. If you let users register, they still can post comments with links, IF they are logged in.
The installation is as simple as uploading the module and enabling it in Drupal.
The user warning can be customized using the translation features of Drupal.
This module was sponsored by The Pickwick Project