I had two different Office 365 subscriptions (because I had taken over another business), so I deleted the domain from one account, and added it to the other.
Now I had both email accounts with their unique domains already setup in Outlook when I did this, and as expected the emails stopped flowing for one of them. So I re-created the mailbox in 365 with the new tenant, and created a new profile in Outlook to try to add that same email address again.
However Outlook keeps failing to add this email account, and I suspect it is referencing some old records which is pointing it to the old tenant, I just don't know where to find it.
I can add the email address on another computer on the same network, but just not this one, so I'm wondering if there are any ways to fix this (short of rebuilding Windows)