Mail users syncing 'mail' attribute to Entra as a secondary address

Gardner, Drew 0 Reputation points
2026-07-08T20:34:04.6766667+00:00

Hello,

We have a hybrid Exchange configuration and sync our Active Directory to Entra. We recently noticed that accounts that are mail users in Exchange have their samaccountname listed for their mail attribute in Entra, and the address from the mail attribute in AD is listed under "Other addresses."

I've confirmed in our sync rules that we don't have any transformations that would modify the attribute (they're set to the default 'Trim([mail])') setting.

Does anyone know why this is happening and how we might correct it?

Thanks!

Exchange | Hybrid management
Exchange | Hybrid management

The administration of a hybrid deployment that connects on-premises Exchange Server with Exchange Online, enabling seamless integration and centralized control.

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  1. Gardner, Drew 0 Reputation points
    2026-07-17T12:38:16.56+00:00

    I've found that the issue seems to be caused by our account creation tool (ManageEngine ADManager). Accounts created through this tool exhibit this behavior, while accounts created directly in AD do not. I will be reaching out to them for further support.

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  2. Hin-V 16,830 Reputation points Microsoft External Staff Moderator
    2026-07-08T22:22:30.0233333+00:00

    Hi @Gardner, Drew

    Thank you for sharing your concern. 

    Based on my research, this issue might be related to how Microsoft Entra ID evaluates Exchange recipient attributes for mail-enabled objects in a hybrid Exchange environment. As far as I know, the primary email address shown in Microsoft Entra ID is not determined solely by the mail attribute in Active Directory. Instead, Entra ID evaluates Exchange recipient attributes together, with proxyAddresses typically taking precedence. If a Mail User has a primary SMTP address defined in proxyAddresses, Entra ID may use that address as the primary email address, while the value from the mail attribute may appear as an additional address. 

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    You can refer more via: How the proxyAddresses attribute is populated in Microsoft Entra ID | Microsoft Learn 

    To ensure I fully understand your situation and provide the most effective assistance, I’ll need a few additional details, such as:  

    Could you confirm whether the affected object is an Exchange Mail User or another recipient type? 

    May I know the values of these Active Directory attributes for one affected user? (such as mail, proxyAddresses, mailNickname, and userPrincipalName) 

    If possible, please also share the output of this command: 

    Get-MailUser <Identity> | Format-List PrimarySmtpAddress, ExternalEmailAddress, EmailAddresses, EmailAddressPolicyEnabled, RecipientTypeDetails 

    In order to better assist you, I will open a private message within this thread. Please share the output of your AD attributes from your side so I can better understand the issue. This approach helps to protect your personal information and prevents sensitive information from becoming publicly visible.

    To view or send private messages, please sign in to the Microsoft Q&A forum with the account that was used to create this thread, and then select "Private messages" 

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    Any updates would be greatly appreciated. 

    Please understand that our initial reply may not always immediately resolve the issue. However, with your help and more detailed information, we can work together to find a solution.  

    Note: Please follow the steps in our documentation to enable e-mail notifications if you want to receive the related email notification for this thread.  

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