Still, that seems like a combo of “comes with the territory of encrypted email” and “their software could use some major improvements”. I think closed platform is closed by design.
comes with the territory of encrypted email
AFAIK they haven’t tried to standardize their implementation, which to me implies that they’re not interested in interoperability. That’s unfortunate. I wouldn’t want to be locked in to a vendor like that.
At least some providers do try. FastMail published the spec for their modern, stateless replacement to IMAP through the IETF as “JMAP”, and built on top of existing RFCs where possible.
Nah, fundamentally proton uses the same encryption as everyone else, they just have a central server to exchange keys rather than one of the open servers.