We use it for corporate mail ... but we all still have google accounts to access google cloud, do oauth to other services, and to manage our calendars.

The UI is clunky and extremely slow. A sidecar app is required to use a local mail client (which is actually quite neat, as it runs a local proxy over a secure tunnel) but it is a hurdle nonetheless

I would not use it for corporate purposes or anything other than a situation where you value 'privacy' over all else.