I think I know the answer, bit maybe I’m missing something
Since proton only sends and receives encrypted emails to other proton accounts, that means that when you get or send an email to someone else, they have to send / receive unencrypted and there is no way for us to verify what they are doing. Right?
Also if most accounts are google Microsoft, they still get 90% of my emails. By switching to proton I think I’ve gained nothing, while losing convenience , added another trust point, and having two different companies have my data instead of just one
Proton drive, calendar and VPN I think are fine
Sorry for the poor syntax. I’m at work working on email related things, and this topic kept distracting me. I might correct it later
Assuming that you trust what Proton says, when they receive a (possibly unencrypted) message they re-encrypt it with your key as soon as possible and they don’t log the content. So, after that point, they (or anyone else) can’t read the email contents. If it was also encrypted in transit, then there’s only a small window inside their email processing system where the plaintext was passed from one encryption to the other. It’s only decrypted again in your browser or proton mail app with the key that only you have. It’s not bulletproof, but it’s better than most providers.