Last month I found a post advising to setup Zen from spamhaus on Movable Type to filter spam. Since then, I've had an alarming number of false positives, i.e. legitimate comments that are junked on the basis that the commenter's IP is listed in one of the Zen databases. By alarming, I mean that when more than half the junked comments are in fact legitimate, it's time to junk the spam filter instead. Looks like it's not that smart anyway.
Has someone else seen the same problem?
Please read the FAQ bloggers. Zen includes the PBL, a list of IP addresses that sould not be sending direct email. But these are the IP addresses everyone using broadband, dialup, etc. are on. Meaning: the IPs that post to blogs! Most legitimate posts will be blocked if one uses this.
http://www.spamhaus.org/faq/answers.lasso?section=Spamhaus%20PBL#190
sbl-xbl.spamhaus.org could be used, but again, read the FAQ
http://www.spamhaus.org/faq/answers.lasso?section=Spamhaus%20XBL#155
Thanks for the FAQ, I suspected something like that. Six Apart should not advise bloggers to use this filter since it's not intended for the same use.
thanks for the info, François. it was killing our blog community too and we couldn't find out the problem.
I commented this information on their announcement, but it got moderated away... they probably prefer to keep wrong information online instead of having to correct themselves.