If I read the slides correctly, their idea is to increase the cost of
sending e-mails with mathematical puzzles, which is seen as acceptable
for a few e-mails, but not for mass e-mails. Mails from an unknown
(=not-yet-whitelisted) sender are put in a 'holdbox', and the
receiving MTA sends a challenge consisting of a puzzle back to the
sender. The sender then has to proof his sincerity by solving the
puzzle, either a mathematical one by automatically expending costly
computation time, or by solving a puzzle made for a human (an image
which you have to read numbers from, like on some web registration
forms).
One of the (many) reasons why this proposal is misguided is the fact that
spammers using armies of spambots have several orders of magnitude more
computing power available to them (to waste in solving such puzzles) than
legitimate senders probably do.
Gordon Peterson http://personal.terabites.com/
1977-2002 Twenty-fifth anniversary year of Local Area Networking!
Support free and fair US elections! http://stickers.defend-democracy.org
12/19/98: Partisan Republicans scornfully ignore the voters they "represent".
12/09/00: the date the Republican Party took down democracy in America.
_______________________________________________
Asrg mailing list
Asrg(_at_)ietf(_dot_)org
https://www1.ietf.org/mailman/listinfo/asrg