O365 username managment

Dan 81 Reputation points


does anybody know if it is possible to use anything else for login then onmicrosoft.com domain when you sync on-prem AD users to Azure AD?

We are using non-routable domain (domain.local) in our on-prem AD and due to some old applications we are not able to change user UPN in on-prem AD (if we change it login to a lot of apps and services break), but we would like to set O365 login to be the same as users email address (user@domain.com). Is there a way to use something different then onmicorosft.com domain for synced users?

Microsoft 365
Microsoft 365
Formerly Office 365, is a line of subscription services offered by Microsoft which adds to and includes the Microsoft Office product line.
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Microsoft Entra ID
Microsoft Entra ID
A Microsoft Entra identity service that provides identity management and access control capabilities. Replaces Azure Active Directory.
19,350 questions
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Accepted answer
  1. James Hamil 21,391 Reputation points Microsoft Employee

    Hi @Dan , you can configure Azure AD to let users sign in with their email as an alternate login ID. This feature enables sign-in with ProxyAddresses, in addition to UPN, for cloud-authenticated Azure AD users.

    However, you need to ensure that the domain in the email address is a verified custom domain in Azure AD. If the UPN suffix doesn't match a verified domain in Azure AD, then Azure AD replaces the UPN suffix with the default onmicrosoft.com domain.

    Please let me know if you have any questions and I can help you further.

    If this answer helps you please mark "Accept Answer" so other users can reference it.

    Thank you,


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  1. Andy David - MVP 140.8K Reputation points MVP

    Any Custom domains must be routeable so they can be verified - so not really possible to do this