Thunderbird using proton bridge
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either the official app or the official web-app. Those are the only two ways you should bother with it.
I only use the webclient (laptop/pc) or the android app.
Edit: i haven't used an email client personally in the past... 25 years or smth?
Professionally I've had Thunderbird, evolution and outlook. Since the companies I work for are always on o365
Haven’t upgraded myself, so I just use the web client or the official iOS app so far.
Same