that was, i believe, the point of decentralized cryptocurrency before it became decentralized cryptocurrency: https://en.wikipedia.org/wiki/Hashcash https://en.

that was, i believe, the point of decentralized cryptocurrency before it became decentralized cryptocurrency: https://en.wikipedia.org/wiki/Hashcash https://en.wikipedia.org/wiki/Hashcash but then it makes email so environmentally unfriendly, may as well just send dead trees. edit: interesting, didn't know the idea of arbitrarily expensive computations as adding costs to combat abuse was first presented in the early 90s: https://en.wikipedia.org/wiki/Cynthia_Dwork https://en.wikipedia.org/wiki/Cynthia_Dwork