Using Mollom to block spam

It's amazing how much spam is generated when commenting is enabled on a blog. When I first launched the Drupal version of, I had commenting enabled for new posts but had it set so that administrator approval was needed before any new comments went live. Coming from a MovableType blog previously, I was used to doing this as I received tons of spam on that blog and had to moderate there as well. It's not a good user experience to expect people to wait until I approve a comment though, so I was keen to let users post directly.

When the site first launched, there were very few spam comments, so leaving comments open seamed feasible, but very soon - as spammers started to pick up on the changes - they started arriving in droves, and that was just on the few comment-enabled posts that I had created since launching.

Not wanting to impede people's commenting with a captcha for every comment, I avoided Drupal's captcha module and instead opted to try out the Mollom module as an interface to the Mollom spam filtering service created by Dries Buytaert, the founder of the Drupal project.

Mollom is a free service that checks all the comments (and/or other forms) posted for known patterns of spam, blocking it where appropriate, and letting real user-created comments through unhindered. If it's not sure whether it's spam or ham (the term for real content), it then presents the user with a captcha that the user can fill in if they have been mistakenly flagged as possible spam.

So far, the service has been great, with 588 spam messages blocked in the past 16 days, the busiest days being Christmas Eve and Christmas Day with 260 spam messages between them. I'm very happy to be a Mollom user! Sorry spammers, it's nothing personal, honest.


Mollom certainly seems to do a good job, but I've had a few complaints from visitors to my site that they can't leave comments sometimes because the module doesn't actually generate an image. Having said that, neither does it let spam through, but I don't like the implication that things are dropping out.

Have you had any problems like that?

I haven't heard of any problems on this site yet but it's still early days, so I'll wait and see if I hear of any problems. Trouble is, it's a bit difficult to test as the images are only generated when they think there could be spam involved.

I as well have encountered the Mollom module does not generate an image as well. I have switched to Captcha for now b/c of that issue.

It looks like there were some others encountering similar issues, with the connection being reset when trying to load a captcha, though limited to certain computers (/network connections).

Your article helped me choose a tool (Mollom) to block spam registration from my drupal account. It was bothering me quite a bit not knowing how many users were really registering each day, plus each of those accounts were then open to submit spam comments on my posts and forum, so I appreciate the help!

How does Mollom compares to ReCaptcha or other captcha service out there? What makes Mollom better?

I think mollom would also do the same work that captcha is doing - keeping off the spammers from the post. Hope this service won't block the genuine comments as blocking such comments invariably would nullify the purpose of comment option.

Dear Condos in Evansville, it's funny that, as an apparent spammer yourself, you wouldn't want an anti-spam service to block spam. Thanks for your comment.