There is a "Bitcoin by email" button which I haven't figured out how to use.
Has anybody sent Bitcoin using someone else's email? It's curious because it indicates some level of centralisation. A set of addresses linked with someone's account. Am I wrong?
I haven't tried it but you can only use it with other proton wallet users. So if you try to input any email that doesn't have a Proton bitcoin wallet, it won't work. You can only create a bitcoin wallet using a proton email address, so yes, they should easily be able to retrieve the addresses associated with your proton wallet using the email you registered from.
@SFR10 Strange, the last thing you would expect from a VPN company is to be strict with this kind of thing.