On Thu, May 29, 2003 at 08:36:55PM -0400, John Stracke wrote:
someone who is sending me a human generated
message can generally easily afford the 2 minutes worth of CPU time
before their mailers can deliver the message to my mail host.)
But what CPU? The machines with which I routinely send mail range from a
200MHz handheld to a 2GHz*2 desktop. I would be unhappy with a protocol
that required me to run my handheld's CPU at full speed for 2 minutes
(the battery life isn't so hot); but that level of hashcash would
Rather than actually force the remote CPU be run for 2 minutes, the
receiving SMTP host can force the TCP window to 0 for 2 minutes. This
could be coupled with a RBL list, but instead of a blackhole, it would
be more like a realtime pushback list (RPL), which has some nice
properties of punishing known abusers, but not causing complete
collateral damage to innocent parties.
John