2. Your mom would likely understand "If unsure, answer No", and end up sending a normal e-mail. That text should be in bold, probably. Some of the verbiage could be behind some "learn more" link, where there is space and scope for a better explanation.
It is probably better if the switch is on the receiver's side, as some kind of Boolean field in the key registration record.
It is pretty interesting seeing the various different design philosophies for computer UIs compete in this thread:
the typical Linux approach (ask the user a convoluted question, expect them to understand it and expect an informed response - if/when the user selects wrong, tough shit)
the Windows approach (ask a convoluted question but give an out for the 99% of people who don't understand it - if the user still selects wrong, tough shit)
the Apple approach (don't ask the question at all and choose a sensible default, because 99% won't care - 99% of users get the exact result they wanted to begin with)
That's exactly what anti-encryptionists would want.
However, we don't want to make it opt-in if we can avoid it, even if that's what would make sense for Linux, Windows and Apple; it's not what would make sense for Proton. You can't change the world by copying someone else :)
But once you leave the ProtonMail ecosystem, I expect you'll find that enabling PGP automatically doesn't work most or all of the time. It likely only works occasionally or even rarely.
> You can't change the world by copying someone else :)
Please take this as gently as I intend it: ProtonMail is unlikely to change the world on user privacy, at least when it comes to email. Larger providers are too entrenched, and most people won't care enough about privacy to change their email address (and very few people have a custom email domain to move between providers).
At any rate, it seems like you're copying Facebook: "move fast and break things". Not great when we're talking about messaging. You're breaking email for some people, and some of those people are your users. OP may not be one of your users, but OP's mom is, and you have broken her ability to send her son email with this misguided policy.
> most people won't care enough about privacy to change their email address
Note that with this change, you don't need to change providers to get end-to-end encrypted email: you can let your email client or a browser plugin (like FlowCrypt or Mailvelope) handle OpenPGP for you, and (let it) upload your key to keys.openpgp.org, and we'll send you encrypted email. Obviously, signing up for Proton is still easier, but email is a federated system, and so I think it's important to invest in the feasibility of federated E2EE as well :)
Otherwise, it seems like you're fine with breaking email delivery to everybody using that ever having published an OpenPGP key (and verified their email address) to the public keyserver.
Privacy was indeed preserved -- at the cost of communication.
This seems like the ideal. If the message could look like
> This message from mom@protonmail.com was encrypted by PGP using the public key for foo@gmail.com retrieved from www.keys.openpgp.org
> -- BEGIN PGP MESSAGE -- ...
Would that leak anything the email provider and every forwarding server couldn't already have known? Not sure if clients support this kind of mix of plaintext and PGP: of course you could put the metadata in the headers, but clients won't show random new headers by default and Google isn't going to help you encrypt messages they would prefer to read.
But that does require all clients to make this easy for the user.
But we don't. And while we don't, users have a reasonable expectation that they can send an email and the other person can read it.
Why even use Proton then? What is the point?
> If unsure, choose "No".