> for non-tech people to use it Then it should be only the SMTP server operators who have to handle the crypocurrency side of things, so email users never have

> for non-tech people to use it Then it should be only the SMTP server operators who have to handle the crypocurrency side of things, so email users never have to worry about it. As you say, acquiring and using the cryptocurrency would be about as technically difficult as what the SMTP server operators are already doing, and there are a variety of 3rd party brokers they can choose if they want to simplify things and not run a node themselves. The system I'm imagining is one where each newly registered domain has to put up a cryptocurrency bond if the registrant wants to send email from it. Existing domains would be grandfathered in (having already built up their reputation) and new domains would have their bonds burned if some N-of-M stakeholders agreed that they were sending (DKIM-signed) spam. Choosing those stakeholders would be controversial, but hopefully no less controversial than the system we have today where Google can use the threat of a Gmail blacklist to make every SMTP server in the world follow its wishes. Ideally some of the stakeholders would be non-profits like the ISRG and Mozilla Foundation.