There's a lot of paranoia in this thread. The whole point of end to end encryption is that it protects against court-mandated searches. (among other things) It doesn't prevent the search, it renders the search less useful.
End to end encryption in email is somewhat silly, because the vast majority of the time you will be sending email to a private company, or to a gmail address, or generally just to another party that will not respect your privacy at all.
The real benefit to something like ProtonMail is that they're not Gmail. They're not scanning every message you send you send and using it to build an advertising profile on you. If you're really worried about government warrants, email is not the tool for you.