Adam Back <aba@dcs.ex.ac.uk>:

How about this alternative which achieves the same functionality and removes the juicy supeona target:

Turn on hashash database for all mails. That means hashcash gets put in the database to prevent double spending. ....

So now when you reply to a message, on it's way out via the mail hub, you remove that hashcash token from the double spending database. This means that the sender can cache sent hashcash tokens, and re-use them when after he gets a reply.

Doesn't this invite the spammer to Bcc an accomplice with the target ISP ? The accomplice replies; thereby freeing the coin for reuse.

I am told by one subscriber to look at TIS firewall toolkits imap program.

You may have meant "smap". -- ############################################################## # Antonomasia ant@notatla.demon.co.uk # # See http://www.notatla.demon.co.uk/ # ##############################################################