I'm in no way a C/R supporter, but I have done some experiments with C/R
in that past. One "enhancement" I quickly discovered was using VERP
tagging on the challenges, and dropping messages from the pending queue
when the challenge bounced. This cut the pending queue by more then 90%.
Russ Nelson has experimented with a R (no C) technique based on this
observation. When a message from an unfamiliar address arrives, his
setup sends an auto-ack and puts the mail into a holding pen. If the
auto-ack bounces, he moves the message into the spam folder. If after
15 minutes or so there's no bounce, the message moves into the inbox.
He said it works quite well.
R's,
John
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