Microsoft Account Errors

How to Fix Wrong Business Email and Tenant Name in Microsoft 365

Rana Garcia Sep 28, 2026 868 views

Question details

Users need to update and correct outdated tenant names or lingering .onmicrosoft.com email addresses that continue to display in outbound messages.

How to Fix Wrong Business Email and Tenant Name in Microsoft 365

Product: Microsoft 365
Device & OS: not provided
Scenario: A business trial was canceled and a new account was created, but administrative details were not fully updated across the system.
Observed behavior: Microsoft 365 apps, such as Bookings, continue to send messages using the old tenant name and an outdated .onmicrosoft.com address instead of the new custom business email.

Before you start

Ensure you have global administrator access to the Microsoft 365 admin center and have your correct custom domain's DNS records ready for verification.

Solution 1Recommended

Verify and Correct Organization Name and Domain Settings

Check your organization profile and active domains to ensure the correct business name and email address are designated as the default.

When switching accounts or canceling trials, lingering data in your tenant configuration can cause apps like Bookings to use outdated credentials. Correcting these from the central admin console is required.

Log in to the Admin Center

Go to admin.microsoft.com and sign in using your global administrator credentials.

Update the Organization Name

Navigate to Settings > Org settings > Organization profile tab. Click on 'Organization information' and update the name to match your current business name, then save the changes.

Confirm Custom Domain Configuration

Go to Settings > Domains. Ensure your current custom domain is listed, verified, and set as the default domain. If the DNS records show errors, follow the prompts to resolve them.

Check User Email Assignments

Navigate to Users > Active users. Select the affected user accounts, click 'Manage username and email', and confirm that the primary email address is using the new business domain rather than the old .onmicrosoft.com address.

Verify and Correct Organization Name and Domain Settings

Propagation Time: Changes to domain configurations, user names, and organization profiles may take up to 24 hours to fully propagate across all Microsoft 365 services and external applications.

Solution 2

Create a Service Request with Microsoft Support

If the outdated tenant name persists in specific apps after correcting organization settings, contact Microsoft support for backend resolution.

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Frequently Asked Questions

Why is my old .onmicrosoft.com address still showing up in emails?

This usually happens because the old domain is still set as the primary email address or default reply address for a user or shared mailbox. You need to update the primary address to your custom domain in the Active Users section of the Microsoft 365 admin center.

How long does it take for organization name changes to take effect?

Changes to the organization profile, custom domains, or user email addresses can take anywhere from a few hours to 24 hours to sync completely across all interconnected Microsoft 365 apps and services.

Can I completely remove the .onmicrosoft.com domain from my Microsoft 365 account?

Microsoft requires every tenant to have an initial .onmicrosoft.com routing domain, so it cannot be completely deleted. However, you can set your custom business domain as the default to ensure the .onmicrosoft.com address is hidden from external communications.

What should I do if Bookings still uses the wrong business name after updating the admin center?

Check the specific settings within the Bookings app itself. Sometimes, business information is cached or was manually entered in the Bookings calendar settings, meaning it must be updated independently from the main Microsoft 365 admin center.

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