While I hardly have a problem with comment spam on Ununique, I host an MT install that has been hit rather hard (on my scale) the last year or so. Daily, 10+ comment spams has been posted to the different sites, and well, I’ve been trying to clean it up, but it gets annoying after a while.
So today I simply added .com to the blacklist. Yes, it’s an extremely desperate solution and won’t even keep all spam out, but well.. the weblogs hosted by the MT installation is personal ones – without many comments except from friends, and to my knowledge, none of those friends have a .com address. So it shouldn’t really block out any legitimate comments.
And hopefully it will block 95% of the comment spam. I can deal with the last 5%, I think :)

