I don’t think think Proton shows bad will on this one. The only alternative I can think of (as a non expert) would be IMAP + GPG encrypted emails but very few desktop clients support GPG, which would make them less accessible 🤷♂️ Having their own protocol also probably makes it much much easier for them to iterate on it, opening up usually makes think much robust but also slower.
On a lighter note, the protocol might be proprietary but the bridge still seems to be fully open source : https://github.com/ProtonMail/proton-bridge
I don’t think think Proton shows bad will on this one. The only alternative I can think of (as a non expert) would be IMAP + GPG encrypted emails but very few desktop clients support GPG, which would make them less accessible 🤷♂️ Having their own protocol also probably makes it much much easier for them to iterate on it, opening up usually makes think much robust but also slower.
The bridge Is “open” but somehow it works only for premium users.