http://www.hashcash.org/ Hashcash is a denial-of-service counter measure tool.
Its main current use is to help hashcash users avoid losing email due to content based and blacklist based anti-spam systems.
Description: postage payment scheme for email based on hash calculations
Hash cash is a payment scheme that uses CPU cycles as the form of payment. This can be used as a counter-measure for junk email (spam) by using the hash cash token as a proof of payment for each email that you sent.
ということでちとみるか。まあ、あわてなくても、 Hashcash is supported in SpamAssassin as of version 2.70. ということなので
待つかなあ。debのspamassassinもすぐに2.70になるだろ。さらに Hashcash is also supported by TMDA and CAMRAM. か。CAMRAMはこれからが楽しみだな。