OT1H, I don't have a horse in the fight about whether you're right or not, but I was curious because if it is a web app they did a damn stellar job
But no, it's a formal android app and I offer two pieces of supporting evidence: the resource browser shows the apk very obviously has a bazillion android resource files <https://imgur.com/a/pUbQ8Bp> and it supports native fingerprint auth
True. I seem to remember that the UI itself did not load when there's no internet connection, but I just tried it, and it does now. So maybe things have changed, or I misremembered.
Either way, no offline access in an email app... pretty bad.
It's not a native app. The main interface where you view your mailboxes, compose new emails, edit settings etc is a web view. The interface doesn't even load if you're offline, let alone your emails. Certainly some parts of the UI are native, but that's true of any web app.
But no, it's a formal android app and I offer two pieces of supporting evidence: the resource browser shows the apk very obviously has a bazillion android resource files <https://imgur.com/a/pUbQ8Bp> and it supports native fingerprint auth