Thunderbird on my pc and the default ios app on my phone for my non proton mail email accounts I just use the proton mail website when I use my proton email

Proton web and mobile client. Also thunderbird

Tuta Mail for personal

Thunderbird/K-9 (mobile) for my work's gmail since the gmail website is garbage

I’ve been wanting something too! What I really want is something that interfaces natively with Exchange server as well as integrated inbox for multiple accounts.

The one product that exists is Blue Mail which is pretty nice except that half its functionality is broken. I’ve been in contact with their support multiple times over many months and eventually they just gave up. Its functionality is limited by arbitrary glitches and unknown limitations which they simply don’t want to bother fixing.

I flip flop between emacs and Thunderbird I use protonmail and both work great Integration with protonmail calendar and drive either is poor or non existant, but I don't use/care about those features anyway

A combination of thunderbird and mutt.

And bluemail on android...

i still have to use windows occasionally, and just run thunderbird on that. When on linux i use aerc because i way prefer terminal applications in general, but also i am lazy and the setup took about three seconds vs. mutt which requires a bit more work.

I recently (months ago) switched back to Evolution from Thunderbird. I used both of them several years. I had a webmail phase in between. Thunderbird has/had enoying issues displaying mail threads.

For calender I switched to gnome-calendar, because it looks very modern.

Thunderbird with the Proton Mail Bridge on desktop, Proton Mail client on mobile although I'd prefer to have all my mails on K9 since I have multiple mail accounts and haven't fully migrated from gmail.