I left the strict matching checked at first because the in the email matched the user in O365 / Entra. However, I have zero problem leaving it unchecked. I'm starting to get my head around this...thanks for the help Kevin!
Now I'm trying to add an additional email account. I am selecting Microsoft OAuth 2 under the Remote Mailbox tab. Under Config, I typed in the new email address and unchecked strict matching. However, it looks like idp config has defaulted back to ground zero?? Do I need to re-fill in the information for the new email account?
Thinking the answer is yes. Filled in and seem to be heading in the right direction. Last error is Resource Owner and Email mismatch despite the Strict Matching box being unchecked.