How to configure correct email in New Outlook when UPN is different to Email address

Question

Hi there, I am a UK Healthcare IT worker. We use the NHS Shared Tenant which means we have O365 as a "managed service". We manage our own local AD. We use SCCM and don't use Intune.

Recently in the migration to Windows 11, there has been an increase in users wanting to use New Outlook. However users can ONLY configure New Outlook if they fire up Outlook Classic, and then use the NEW Outlook toggle.

Its almost impossible for a user to login directly to New Outlook. It just assumes your UPN (which is domain specific and not email routable) is your email address. Which it isn't our email address is @domain.net - which is correctly populated in our mail AD attribute.

We have spent ages on this issue with no resolution. We have tried:

PreferProvidedEmailInAutoDiscoverAuthPrompts

from: https://learn.microsoft.com/en-us/previous-versions/troubleshoot/outlook/unexpected-autodiscover-behavior

We have systematically worked through each and every option here =
https://learn.microsoft.com/en-us/microsoft-365-apps/outlook/profiles-and-accounts/control-autodiscover-via-group-policy

Most recently, we found a new "silver bullet" registry key to try:

Outlookforwindowsprimaryaccountmustmatchdevicesigninaccount

from: https://learn.microsoft.com/en-us/microsoft-365-apps/outlook/manage/policy-management

and nothing sticks. the only reliable method we have found is to intentionally mispell the email domain ndomain.net (for example) which causes the lookup to fail, and then we can type in the correct email domain (either that, or launch new outlook from outlook classic)

anyone got a more elegant solution? (adjusting UPN isn't an option at this time, because of the Shared Tenant)

Answer 1

To configure the correct email in New Outlook when the User Principal Name (UPN) differs from the email address, you can try the following approaches:

1. Use the Classic Outlook Profile Setup: Since you mentioned that users can only configure New Outlook after launching Outlook Classic, ensure that users create their profiles in Classic Outlook first. This may help in setting the correct email address before switching to New Outlook.
2. Registry Key Adjustments: You have already tried several registry keys. Ensure that the following keys are correctly set:
   • PreferProvidedEmailInAutoDiscoverAuthPrompts to prioritize the provided email address during authentication prompts.
   • Outlookforwindowsprimaryaccountmustmatchdevicesigninaccount to enforce matching accounts, though you mentioned this did not yield results.
3. Manual Entry: As a workaround, you can continue to use the method of intentionally misspelling the email domain to trigger a manual entry prompt. This is not ideal but can serve as a temporary solution until a more robust fix is found.
4. Check Autodiscover Settings: Ensure that the Autodiscover CNAME record for your domain is correctly set up. This can affect how Outlook retrieves the necessary settings for account configuration.
5. Contact Microsoft Support: Given the complexity of your environment (NHS Shared Tenant), it may be beneficial to reach out to Microsoft Support for tailored assistance, especially since adjusting the UPN is not an option.

These methods may help alleviate the issues users are facing with New Outlook configuration.

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References:

• Outlook can't set up a new profile by using Exchange Autodiscover for an Exchange Online mailbox in Microsoft 365
• You're repeatedly prompted for credentials when using modern authentication in Outlook 2016 for Mac

Answer 2

Please note that our forum is a public platform, and we will modify your question to hide your personal information in the description. Kindly ensure that you hide any personal or organizational information the next time you post an error or other details to protect personal data.
Hi @Jaime Watson 
Thank you for contacting the Microsoft Q&A forum.   
I truly appreciate the detailed information you shared about your current situation and the steps you’ve tried so far. This helps me better understand your scenario and narrow down possible solutions. From what you described, it seems that the New Outlook is using your local account rather than the shared tenant email account. 

As forum moderators, we don’t have access to a dedicated testing environment that matches your shared tenant setup, so we’re unable to fully replicate and test potential solutions. To confirm visually, could you please share a screenshot of the outlookforwindowsprimaryaccountmustmatchdevicesigninaccount value in the Registry Editor? This wasn’t clearly mentioned in your description. 

The value of this registry key should be set to 0, which disables using the Windows sign-in account as the primary account for New Outlook. 

Please share the screenshot via private message to protect your privacy and make it more convenient for you. You can check your inbox for an email with the subject “New private message on Microsoft Q&A question” to view my response. 

Additionally, could you confirm whether, after using the workaround (switching from Classic Outlook to New Outlook), the issue still persists when you open New Outlook initially? 

If you have any further questions or updates, please don’t hesitate to reply. I’m happy to assist you to the best of my ability. 

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