Using Outlook for iOS in business environments for email and scheduling
Hi Raymond,
Thank you for sharing the details of your situation.
As this is a user-to-user community forum, I do not have the ability to directly access or modify your account or service. However, I can provide guidance, recommend next steps, share applicable resources, and direct you to the appropriate support channels so the issue can be investigated further.
Based on your description, the domain has been moved to the new Microsoft 365 tenant while the users’ email addresses remain the same. The affected iPhones may still have an authentication or device-management association with the previous tenant. As a result, Microsoft apps may detect both the old and new account identities and display the duplicate account message.
Since you have already cleared and reinstalled the applications and removed the account from within the apps, I recommend focusing on Microsoft Authenticator, Company Portal/Intune enrollment, and the iOS management profile. These components can retain organizational account information outside Outlook or Teams.
Before removing the account from Microsoft Authenticator, please ensure that the user has an alternative MFA method or can re-register MFA in the new tenant.
1/ Remove the old account from Microsoft Authenticator
- Open Microsoft Authenticator.
- Select the account associated with the previous tenant.
- Open the account settings and select Remove account.
- Restart the iPhone afterward.
- Reference: How to sign out from Microsoft Authenticator
Removing the account will also prevent that iPhone from approving MFA requests for the old account.
2/ Check for an old Company Portal enrollment
- If Microsoft Intune Company Portal is installed, open it.
- Go to Devices and select the affected iPhone.
- Select Remove device.
- Unenrolling may remove access to the old organization’s email, applications, Wi-Fi, VPN, and other protected resources.
- Reference: Remove your iOS device from Microsoft Intune
3/ Check the iOS management profile
- Go to Settings > General > VPN & Device Management.
- If a management profile belonging to the previous organization is listed, remove it if permitted.
- If the profile cannot be removed, the previous tenant’s Intune administrator may need to retire or delete the device.
4/ Restart and test the new account
- Restart the iPhone.
- Open Outlook first and add only the account from the new tenant.
- If the sign-in page suggests the cached account, select Use another account and manually enter the email address.
- If the account is also being added to Apple Mail, select Microsoft Exchange, not Outlook.com, for a Microsoft 365 work account.
Should the issue continues, please ask the previous tenant administrator to verify and, where appropriate, retire or delete any old iPhone association in Microsoft Intune, Microsoft Entra ID, or App Protection/mobile application management registration, while the new tenant administrator reviews the failed authentication attempt in the Microsoft Entra sign-in logs to determine whether it is being routed to the previous or new tenant.
Additionally, if needed, you or your IT team can also raise a support ticket with Microsoft Support through the Microsoft 365 Admin Center for deeper investigation. They have access to backend configurations and can perform a more in-depth investigation. At the very least, they can provide the most effective workaround to ensure your experience remains smooth and secure.
- For detailed guidance on how to open a support ticket with Microsoft Support, please refer to: Get support - Microsoft 365 admin | Microsoft Learn
I hope this information is helpful. Should you have any further questions or need additional assistance, please feel free to share them in the comment below. I'm very happy to help.
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