Earlier quoted context omitted.
I agree with everything, just want to add a downside of proton which is often forgotten: there is no search. You cannot search your emails’ body (headers work, but keywords like “from:” still do not work for search), you cannot search the content of your files, etc. It’s the price of end-to-end encryption. The only workaround is synchronising everything locally and searching locally.
But you still can use Thunderbird for that. I recommend it no matter what mail provider is used. Web interfaces are so heavy nowadays, compared to that, Thunderbird feels so fast.
I tried synchronising the data directly in the browser, without any email client and the search is mediocre and slow.
This is not a great experience for search.
But again, it’s not a critique of Proton, it’s just how it is with E2EE. At least it demonstrate they are really doing E2EE.
I still hope some time in the future homomorphic encryption will help, but I think we are at least a decade away from that.