Sign-in & Login Problems

How to Change Microsoft 365 Sign-In Domain for a User

Olivia Miller Oct 10, 2026 870 views

Question details

The user needs to change a Microsoft 365 user's primary sign-in name (User Principal Name) to a different domain within the same tenant, as changing the email alias does not update the login credentials.

How to Sign In with a New Domain in the Same Microsoft 365 Tenant

Product: Microsoft 365 Admin Center
Device & OS: not provided
Scenario: Updating a user's sign-in credentials to reflect a newly added and verified domain within an existing Microsoft 365 tenant.
Observed behavior: Changing the primary email address or default domain leaves the old sign-in name intact, requiring a separate administrative update to the User Principal Name.

Before you start

Ensure you have global admin privileges in the Microsoft 365 admin center and that the target domain (e.g., domain2.com) has already been successfully added and verified in your tenant.

Solution 1Recommended

Update the User Principal Name (UPN) in the Admin Center

Manually change the user's username and domain in the Active Users section so they can sign in using the new domain.

Updating a user's email aliases does not automatically change their sign-in credentials. You must edit the username directly to alter the User Principal Name (UPN) used for logging into Microsoft 365 services.

Access the Microsoft 365 Admin Center

Navigate to Active Users

In the left-hand navigation menu, click on 'Users', then select 'Active users' from the expanded list.

Select the Affected User

Scroll through the list or use the search bar to find the user whose sign-in domain needs to be updated. Click on their display name to open the properties panel on the right side of the screen.

Edit the Username

Under the 'Account' tab, click on 'Manage username and email' or the 'Edit' link located next to the user's current username/User Principal Name.

Apply the New Domain

In the primary email address and username section, click the drop-down menu containing the list of verified domains. Select the new domain (e.g., domain2.com), click 'Save changes', and instruct the user to test their new sign-in name.

Update the User Principal Name (UPN) in the Admin Center

Synchronization Delay: It can take up to 24 hours for the new sign-in name to fully propagate across all integrated Microsoft services like Teams, SharePoint, and Outlook. Advise the user to allow some time for synchronization if they experience immediate login issues.

Free Microsoft Office alternative

Switch to WPS Office for a Lightweight and Hassle-Free Alternative

While Microsoft 365 requires complex domain management and costly recurring subscriptions, WPS Office offers a free, lightweight, and highly compatible productivity suite. You can open, edit, and save Word, Excel, and PowerPoint files locally or via the cloud without navigating extensive admin centers or managing tenant configurations.

1. Download and Install WPS Office: Visit the official WPS website, download the free installer, and follow the on-screen prompts to complete the installation.
2. Open Your Documents: Launch WPS Office and directly open any existing Microsoft Word, Excel, or PowerPoint files without needing conversion or a special login.
3. Save and Share: Edit your documents and save them in their original formats to ensure seamless sharing with colleagues who still use Microsoft Office.

Fully compatible with Microsoft Office formats including .docx, .xlsx, and .pptx.No complex tenant administration or domain sign-in issues to manage.Lightweight installation with an intuitive, familiar user interface for quick adoption.Completely free to use, saving significant software subscription costs.

microsoft office alternative - wps office

Frequently Asked Questions

Why didn't my Microsoft 365 sign-in name change when I changed my email address?

In Microsoft 365, the primary email address (alias) and the sign-in name (User Principal Name) are separate attributes. Changing the email alias does not automatically update the sign-in name; it must be updated separately in the Admin Center.

How long does a UPN change take to sync in Microsoft 365?

While the domain change in the admin center is applied immediately, it can take up to 24 hours for the new User Principal Name to fully synchronize across all integrated Microsoft 365 services, such as Teams and Outlook.

Can users change their own sign-in domain?

No, changing the User Principal Name or sign-in domain requires administrative privileges. Only an IT admin with access to the Microsoft 365 Admin Center or Azure Active Directory can perform this action.

Login & Account Issues