The proton vpn people are either using or working on using block chain as a sort of email verification. Iirc it won’t have any cost or change in usage to the consumer, just an added layer of security. I’m not smart enough to understand how but it sounds neat.
I may have misread, Its not clear to me if it’ll be a staple of their free email service or will be added as part of their paid subscription to all their services but it still sounds neat. It very well could be bullshit but I’m interested in learning more.
https://www.tomsguide.com/news/proton-mail-to-use-blockchain-to-verify-recipients-email-addresses