> I was just told by a guy trying o sell me www.sendio.com that it > blocks 100% of all spam with zero false positives! Are you telling me > he is a liar?
He's definitely lying. Consider the case when some "protected" employee signs up for a newsletter....sent by an automated system...unable to deal with C/R. You just had a false positive. Consider the case where a spammer joe jobs me and I get spammed by the challenge. I will answer the challenge and you get to enjoy the spam too. There's your false negative. While not trivial, it doesn't seem out of the realm of possibility that a spammer can automate responding to certain well known vendors of C/R systems. You now have a whole flood of spam on your hands since the filters suck due to relying on the C/R. The salesperson is obviously ignoring this: <http://linuxmafia.com/faq/Mail/challenge-response.html> ~JasonG -- ~ Ninja Email Security with Cloudmark Spam Engine Gets Image Spam ~ ~ http://www.sunbeltsoftware.com/Ninja ~
