Challenge/Response, good or bad

I've just put up a new essay on my web site on whether challenge/response anti-spam systems are good or bad

As some may know, I've been running such a system longer than anybody, having written one in 1997. I wrote a white paper on best practices for such systems that some have found useful.

However, I also see a lot of complaints about C/R systems. Most of those complaints are about the new crop of C/R systems, many of which have annoying bugs. Because some of the concerns are real, however, I felt it was time for an article on those issues for a well-behaved C/R system.

Note that even my own system, in spite of being better behaved that most newer systems, does not meet all my own best practices, though it would if I were writing it again.

Do any current C/R anti-spam products meet all of your criteria

Hi Brad,

I was investigating C/R anti-spam as I know some folks use it and it must be a God send as far as removing spam. As I'm sure many folks are, I'm concerned that it will annoy some folks, as well.

I like the criterion in your essay at

Are you aware of current or forthcoming C/R anti-spam that meet all your criterion?

Best Regards,
David Geer - Your on time technology writer!

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His name is Brad Templeton. You figure it out.
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