Comment by eatbitseveryday

> Protonmail chose to be incompatible with this established standard.

They've supported receiving PGP-encrypted emails[1] and are working on IMAP support currently[2]. Would be nice for you to cite sources before making strong claims like "chose to be incompatible". Everything is a feature and needs time to implement.

[1] https://protonmail.com/support/knowledge-base/using-protonma...

[2] https://protonmail.uservoice.com/forums/284483-feedback/sugg...