Mollom helps you stop comment spam, contact form spam, forum spam, fake user accounts, etc. To do so, Mollom combines context analysis and accessible CAPTCHAs to optimize your site's accessibility and experience.
The web is changing. User contribution is now what makes or breaks a site. Allowing users to react, participate and contribute while still keeping your site under control can be a huge challenge. Mollom is a web service that helps you identify content quality and, more importantly, website spam. When moderation becomes easier, you have more time and energy to interact with your web community.
Mollom is currently used by several big companies like Adobe, Sony BGM, Warner Bros, IDG and FastCompany.
Unpack in your modules folder (usually /sites/all/modules/) and enable under Administer > Site Building > Modules.
· Drupal 5.x/6.x/7.x