794 votes279 comments · Outlook for Windows (Desktop application) » Settings · Flag idea as inappropriate… · Admin →
An error occurred while saving the commentAnthony D. Green commented
OMG I was able to change mine by first creating the mailbox in the Windows 10 Mail Control Panel. After setting it up but before opening Outlook, I navigated the the Registry keys described in this article. https://www.slipstick.com/exchange/primary-account-removed-outlook/
I found the reference to the account email address and updated them to what I wanted it to display (a different email address) then opened up Outlook and the mailbox used that name rather than the email I logged in with. This was critical to me because my outlook.com email address is a very strange GUID (garbled number) and not the email address I normally send/receive with. So I wanted the Mailbox to use that name and not the one on outlook.com's servers. I can usually login to MS services with either address though.