[hashcash] a few more thoughts to chew on

as I was moving boxes and furniture out of my aunt's apartment this weekend, it occurred to me that if anyone felt like experimenting, twopenny blue has all of the components you need to build a client-side stamper that can use either naïve or Send once stamping protocols. The current downfall will be the inability to communicate message delivery failures to the user. It's not say it can't be done, but we will need to do things a little differently.
If I had infinite spare time and money, I would start with postfix_stamp_feed as the SMTP level interface to the MUA. If you follow the code, it would put messages immediately onto the queue (file_queue). Then the daemon postfix_stamper generates the stamp and sends a message to the designated upstream SMTP receiver. This rough system has the properties of MUA independence, platform independence, resilience across power failures and hiding spam generation delays from the user. Problems include manual configuration issues and that messages that don't need stamps must wait behind any messages in the queue of meeting stamps. I see that as a future feature. :-)
the prototype suggested is not perfect and may not even be practical but it puts you a step closer to client-side stamp generation that is platform and MUA independent.
Have at it. As soon as I figure out how to run a bzr public repository, I will even support it here. 

---eric

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