We're in a bit of a bind here. One of our VIP users can't access Outlook after their Teams password was reset, and despite having an on-prem Exchange 2019 setup with Microsoft Office Pro 2021, Outlook keeps trying to connect to Microsoft 365 instead. I've already tried a bunch of troubleshooting steps like removing Microsoft 365 licenses, clearing their credentials in the Credential Manager, signing them out of all Office apps and Teams, and even creating a new Outlook profile. Still, the autodiscover feature is prioritizing Office 365 endpoints. This user can access their emails fine on their laptop and phone, but I need a solution that ensures Outlook connects only to our on-prem Exchange. Is there something in the registry or an autodiscover override I might be missing? I attempted a registry update (setting `ExcludeExplicitO365Endpoint` to 1) but that didn't solve the problem. Any ideas?
4 Answers
I remember a similar issue a while back. It may have to do with fixing certain user attributes in Active Directory—maybe one of the msexch values or target address needs tweaking. If I find time later, I can look into it more. Good luck with it!
Also, did you ensure the user's email and UPN match? That can often lead to connection issues like this.
Have you checked if the Autodiscover and DNS entries are properly configured in your local DNS? That might be affecting the connection.
You might want to try deleting the contents of the OneAuth and IdentityCache folders in AppData. After that, restart Outlook and see if that helps.
Yes, I’ve double-checked that, and the issue is only happening for this one user.