LISNews has been running on Drupal for about a year now. Before that we ran on Slashcode for a few years, before that it was PHPSlash for a couple years, and even before that I did it all by hand. If you run (or read) blogs you know comment spam is a big problem. If all you do is run or read a blog you actually have NO idea just how bad it really is. I'd estimate about 80% of all POST requests to all the LISHosted sites are spammers. When I have LISNews on the LISHost servers I worked hard at fine tuning the mod_security rules to combat spam.
Within hours of moving to Ibiblio I could see they have very different rules, and I'd need to do something else. I'm actually surprised just how good my rules were working. So I turned on CAPTCHAs. I tried some images, reCAPTCHA, Math, and finally the basic text CAPTCHAs to fight spam. They also worked. A few weeks ago I got a complaint that the CAPTCHAs were getting in the way. This wasn't the first time, so I thought I'd try something new, I turned to Mollom.
I was shocked that within a day the number of comments went up. It's been a few weeks now, and I continue to be shocked at the number of comments we're seeing. Mollom is doing a decent job blocking spam, but more importantly it's letting more people comment. The bad guys are kept out (for the most part) and the good guys have a very low hurtle to get over. (Or at least I think so. If the current trend holds, then I'll be convinced that it is indeed Mollom and not just a coincidence). Two charts that illustrate what I'm seeing on this end
1. The number of comments per day over the past 90 days. You can see the big upward trend cutting right through the middle.
2. Mollom generates these nice little graphs to show you how much it's blocking and allowing. The big orange area is spam, the small green area is real. The numbers here surprised me right away, Mollom catches just about everything that mod_security now misses.
So to summarize, this is exactly what I've been looking for, I love Mollom. It does a really good job (not perfect) of blocking garbage spam comments, and apparently does a really good job (better than standard Drupal CAPTCHAs) of letting real people leave real comments. I guess we can debate how much of that is garbage :-)