[jsnell]

It's the first bullet point in their reasons for dropping the support. About 1% of their users are on IE.

[mbell]

On average IE 11 is around 2% in the US, obviously it'll vary based on the type of site but I would have expected ProtonMail to be even lower.

[sbr464]

Since there are so many users with browsers, I'd be curious if data is available that filters out consumer users/residential IP addresses etc. To better understand business browser usage and get more usable percentage figures.