'File' and other toolbars in new Outlook 2023

Its going to be a good long time before that app replaces Outlook desktop. It will replace windows mail at some point in the future (I don't know when... but will guess maybe the fall?)

The new Outlook is lacking too many features business users need.

I have fallen back on the Office 16 version of Outlook. It works reliably for me with my existing btinternet e-mail address. I could not find any way to add this to the 365 integrated version: no tab or three dots etc. I read elsewhere that Microsoft are now only allowing gmail additions to the 365 Outlook, but Bing claims btinternet should work. My gmail address certainly works on the 365 version.

There is no difference as to the actual Outlook Pre software- its the same if you have the toggle or not. If at least one account in the Outlook profile isn't supported in the new outlook, the toggle shouldn't be shown.

Getting started with the new Outlook for Windows - Microsoft Support

If you get the new Outlook from the windows store, it wont have the toggle.

It's possible to hide the toggle using a registry key -

HKEY_CURRENT_USER\Software\Microsoft\Office\16.0\Outlook\Options\General
DWORD: HideNewOutlookToggle
Value: 1

If you don't have the choice of the good Outlook when you search for outlook (as seen in my screenshot), the good Outlook is here -

C:\Program Files\Microsoft Office\root\Office16\OUTLOOK.EXE

or

C:\Program Files (x86)\Microsoft Office\root\Office16\OUTLOOK.EXE

Open it and pin to start menu and taskbar.