Forum Discussion
Adding domain to Office 365 caused outlook to point to office 365 instead of on-premises exchange
atirhi I just see this post by coincidence, we had such migration as well and had the same issue as you have experienced with around 100 users.
As far as we have understood, this is due to Outlook's Direct Connect feature which checks against Exchange Online by default and bypasses regular AutoDiscovery if a verified domain is found. If your users also have an Exchange Online license (e.g. if you are using Teams Exploratory licenses or M365 Business, these are applied by default) your users already have an additional cloud only mailbox. So Outlook finds two mailboxes and is kinda confused.
https://www.gothamweb.com/portal/index.php/knowledgebase/8/Outlook-bypasses-AutoDiscover-and-connects-directly-to-Office-365-mailbox.html
You can remove all Exchange Online licenses of your users or continue with a proper Exchange Hybrid deployment. Alternatively you can set the following reg setting on all clients in order to suppress this behavior.
[HKEY_CURRENT_USER\Software\Microsoft\Office\16.0\Outlook\AutoDiscover]
ExcludeExplicitO365Endpoint=dword:00000001
thank you very much. This is exactly what is happening. I will try the solution, but changing the registry record could be time consuming with staff at several places. Any ideas to auto deploy it?
thank you.
- Easiest way is to create a GPO with this reg setting and apply it to your users.
If you want to remove the licenses, it depends how your infrastructure is built, do you already have Azure AD Connect established?
If yes, I would create a new Security Group like "M365 Business" and apply it to all affected users. Then in M365 admin console, remove every license assignment to you users. Instead use this newly created AD group and assign the M365 license to the group, there you can remove Exchange Online plan for the whole group at once. After this is processed, all users have this predefined set of licenses.
If you have no AAD sync in place, you can either start with this, but then you might face other issues during initial sync as the local AD users might not map with the already existing cloud users and result in a mess - we had assistance from a certified partner for this step. Then it might be the fastest to to click though every user and remove the Exchange Online plan manually..thank you. we don't have AAD. Will do a manual test. Last question: Will updating office applications in the future reset the registry record again?
thanks again
