The lack of native Microsoft Outlook support was one of the reasons I've abandoned Thunderbird.

However, it is still not enough for me to come back. Sadly, corporate life is often organised around email and calendaring. All these endless meetings everyone complains about, which need to be scheduled, accepted, rejected, re-scheduled, etc. The native Exchange support does not yet support Calendar integration. Without it, it will be very awkward to use in a day-to-day corporate environment.

I barely ever open outlook at work. In fact I only open it on the webmail when someone asks me on teams if I have read their email.

Much quieter that way as you only get to hear about the important stuff and can ignore the rest of the noise.