Why Challenge-Response is a Bad Idea

Of all the ideas for blocking spam, challenge/response is one of the worst.  Check the links at the bottom to see why.

We receive a fair amount of email here, and we try to respond to most of it, however, we do not have the time to fill out a form every time one of our replies is met by a challenge/respond bot.  So, if you are using challenge/response to block spam, you probably will not hear back from us.  (Or from a lot of other sites.)  Please don't take it personally.

http://en.wikipedia.org/wiki/Challenge-response_spam_filtering
http://tardigrade.net/challengeresponse.html

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