User's mailbox accidental changed to user@*.onmicrosoft.com

Question

Hi Team,

Currently we are using Microsoft 365 email service , with Azure Active Directory Connect: This service is responsible for synchronizing on-premises Active Directory with Azure Active Directory".

My 365 primary email domain is "mycompany.com" , all user email come with user@mydomain.com. but we have experienced the issue that user's email display are automatically changed to "user@mydomain.onmicrosoft.com".

it happens randomly and we got complain from user.

I have checked and did not found any change on system or from administrators.

Can you please support me to find out what is issue here?

Thank

Answer 1

Hi @Nguyen Khoa Van ,

Welcome to our Q&A forum!

Since you have mentioned that you are synchronizing on-premises Active Directory with Azure Active Directory with Azure AD connect, please clarify does this issue occurred after running the process?

If so, this issue may occur if there are duplicate SMTP proxy addresses in your local directory or in Microsoft Entra ID. To resolve this issue, you need to find and remove the duplicate addresses so that they are unique for each user.

you can use the Get-MsolGroup or Get-AzureADGroup cmdlets to find the objects that have the same SMTP proxy address. For example, you can run the following command:

Get-MsolGroup -SearchString user@mydomain.com

Besides, AAD Connect has its add-in Troubleshooting Tool, which can help admin to troubleshoot configuration settings such as Object synchronization, hybrid deployment .etc. You can refer to: https://www.sikich.com/insight/troubleshooting-microsoft-azure-ad-connect-powershell/

Please Note: Since the web site is not hosted by Microsoft, the link may change without notice. Microsoft does not guarantee the accuracy of this information.

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