Last March I provided a progress report on the effectiveness of MT-Blacklist, an add-in to the Movable Type software that runs this blog. In the first 75 days after I installed it, it blocked just under 10,000 comment and trackback spams. In the 105 days since that report, spammers have gotten more persistent but haven’t succeeded in breaking through.
Since March 1, MT-Blacklist has blocked 267 spam attempts a day, more than 95% of them automatically. That’s up from 146 per day in the first quarter. The higher number is probably attributable to the increased popularity of this site. Still, as I said in March, I honestly don’t know what I would do without this add-in. And I’m also not sure what I would do if I ever met a comment spammer face to face.
Ed Bott 
So that explains why my comments haven’t shown up!
I’m guessing your server isn’t running mod_security. It runs on my server and it filters out about 95% of comment spam at the server level.
Interesting. I Googled it and it sounds like a fairly new solution. I just pinged my server admins to ask about it.
Thanks!