[artursapek]

If you want to build something which can't be compatible with popular standards, what is the better choice? Build it anyway, or let those standards stop you? It's the same reason I can't read my PGP-encrypted email on my phone.

[lwhalen]

Do what Fastmail did, and work with the community (generally via the IETF) to make your new standard open and compatible:

https://fastmail.blog/2019/08/16/jmap-new-email-open-standar...

[artursapek]

Good point, perhaps Proton will do so.