Email is a tottering stack of standards which mostly-but-not-completely solve problems discovered over time. As the article states it would be a good target for a complete rethink, but I don't think any of the solutions presented are promising avenues to explore.
As one example, consider the proposed "recipient stamps". It requires a complex trust configuration, always-on email clients, and synchronizing 'stamp books' across different clients. I expect that makes it intractable in practice.
Better would be 'postage' where each email contains references to one or more payment methods. The receiver and intermediaries can then deduct a fee from any available payment methods at their discretion. Some common postage methods would be a hashcash service, or crypto-currency address, or pre-approved captcha credits, or a service to request a moderately large Internet transfer.
Yes, great. So then every email leaves a digital financial footprint to trace! Which also, (in the U.S.) means you need a bank account. That bank, requires KYC. You've just removed the houseless and poor from the emailing public.
As one example, consider the proposed "recipient stamps". It requires a complex trust configuration, always-on email clients, and synchronizing 'stamp books' across different clients. I expect that makes it intractable in practice.
Better would be 'postage' where each email contains references to one or more payment methods. The receiver and intermediaries can then deduct a fee from any available payment methods at their discretion. Some common postage methods would be a hashcash service, or crypto-currency address, or pre-approved captcha credits, or a service to request a moderately large Internet transfer.