>> >>> One scheme that seemed to me to have some promise was to detect spam
>>> in the SMTP receiving program and deliberately delay its responses
>>> to the sending program. So that the transaction of sending a message
>>> is stretched out far longer than normal.
>> That's called tarpitting. It would work against spammers who use
>> their own resources to send. Those who use armies of zombies wouldn't >> care.
> I would think that at least it cuts down on the amount of spam, if
> enough of the zombies get stuck in tarpits.
It would, if access to zombies were the limiting factor. It isn't.
Also, a lot of spam engines are written so that tarpitting doesn't slow them down (but the machine doing the tarpitting never gets the message, so there's some benefit there).
Seth