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
