Interestingly, some of bitcoin's roots originate from spam fighting. The idea of the 'proof of work' function that is used by bitcoin came out of the idea of Ha

Interestingly, some of bitcoin's roots originate from spam fighting. The idea of the 'proof of work' function that is used by bitcoin came out of the idea of Hashcash http://www.hashcash.org/ http://www.hashcash.org/ (as referenced in Satoshi's white-paper). The hashcash idea wasn't so successful, although it's still around and somewhat useful. One problem of hashcash was that the difficulty didn't adjust, making it somewhat unfair, not taking in account GPUs, etc. On the other hand, bitcoin solves the difficulty problem that was with hashcash. Perhaps in the future, bitcoin could be used for ensuring the smooth delivery of priority emails.