How to change onmicrosoft.com domain in Microsoft 365

You cannot rename an existing onmicrosoft.com domain, but you can add a new onmicrosoft.com domain in the Microsoft 365 admin center and make it your fallback domain.

This guide covers both admin center steps, moving user sign-in names to the new domain, renaming SharePoint and OneDrive URLs with PowerShell, and the limits that cannot be undone.

Can you change the onmicrosoft.com domain name?

Add a new onmicrosoft.com domain from Settings > Domains > your current onmicrosoft.com domain > Add onmicrosoft domain, then open the new domain and select Make fallback domain. Microsoft does not rename or delete onmicrosoft.com domains. Changing the fallback domain swaps the default for new usernames, group aliases and email routing, but existing SharePoint and OneDrive URLs keep the old name until you run a separate SharePoint domain rename.

Which onmicrosoft domain change do you need?

The word "change" covers three different jobs in Microsoft 365. Match what you want people to see to the right fix.

What you want to change	Do this	Why
The default domain for new usernames and group aliases	Add a new onmicrosoft.com domain and make it the fallback domain	Only one onmicrosoft.com domain can be the fallback at a time
Existing users' sign-in names	Edit each user's username under Manage username and email	Changing the fallback domain does not rename existing accounts
SharePoint and OneDrive URLs such as contoso.sharepoint.com	Run a SharePoint domain rename in PowerShell	SharePoint URLs stay on the original onmicrosoft.com name even after a fallback change
Email addresses that show your brand, such as [email protected]	Add a custom domain you own	Microsoft recommends onmicrosoft.com domains only for testing, not regular email

Onmicrosoft domain limits and admin roles

Requirement or limit	Detail
Admin role	Domain Name Administrator on a business or enterprise plan; custom admin roles and regular users cannot add or change domains
Maximum onmicrosoft.com domains	Five per Microsoft 365 tenant, including the original
Deleting an onmicrosoft.com domain	Not possible once it is created
Fallback domains	Only one onmicrosoft.com domain can be the fallback domain
Scope of the change	The whole tenant, not one user
Role for the SharePoint rename	At least SharePoint Administrator
Role to edit usernames	User Administrator or higher

Check the spelling of the new name twice before you add it. A typo uses up one of your five slots for good.

Step 1. Add onmicrosoft.com domain in Microsoft 365

If you also plan to rename SharePoint, first check that the name is free: open https://newname.sharepoint.com in a browser. A not-found (404) message usually means it is available, while a sign-in page means someone already uses it.

1. Sign in to the Microsoft 365 admin center at admin.microsoft.com.
2. In the left navigation, select … Show all, then expand Settings.
3. Under Settings, select Domains.
4. Select your current onmicrosoft.com domain in the list.
5. In the About this domain section, select Add onmicrosoft domain.
6. In the Domain name box, type the new name.
7. Select Add domain and wait for the message confirming the domain was added.

Do not use the Add domain button at the top of the Domains page for this. That button adds a custom domain and does not create an onmicrosoft.com domain.

Step 2. Change your onmicrosoft.com domain in Microsoft 365

This step makes the new domain the fallback domain. If you want to rename SharePoint to the same name, skip this step for now: Microsoft's SharePoint rename steps say not to make that domain the fallback domain.

1. In the Microsoft 365 admin center, select … Show all > Settings > Domains.
2. Select the new onmicrosoft.com domain you added in step 1.
3. On the domain's property page, select Make fallback domain.
4. Wait for the message that says your fallback domain changed to the new domain.

Change user sign-in names to the new onmicrosoft.com domain

A new fallback domain does not rename people who already have accounts. Edit each username you want on the new domain.

1. In the Microsoft 365 admin center, go to Users > Active users.
2. Select the user's name.
3. On the Account tab, select Manage username and email.
4. Edit the Username if needed, then pick the new onmicrosoft.com domain in the Domains box.
5. Select Done.
6. Repeat for every user who should sign in with the new domain.

For accounts synced from on-premises Active Directory, Microsoft notes that some details can only be edited in the local directory. Microsoft Graph PowerShell can update the UPN with Update-MgUser -UserId old@domain -UserPrincipalName new@domain.

Rename the SharePoint onmicrosoft.com domain with PowerShell

SharePoint and OneDrive URLs are built from the original onmicrosoft.com name and do not follow a fallback change. Microsoft renames them with the SharePoint Online Management Shell, which runs on Windows only.

Add the new onmicrosoft.com domain first (step 1), confirm it shows as Healthy on the Domains page, then connect with Connect-SPOService -Url "https://contoso-admin.sharepoint.com" using your current admin URL.

Start-SPOTenantRename -DomainName "fabrikam" -ScheduledDateTime "2026-11-07T22:00:00"

-DomainName is the part before sharepoint.com or onmicrosoft.com. -ScheduledDateTime must be at least 24 hours and no more than 30 days ahead, in your computer's local time. Run Stop-SPOTenantRename to cancel before it starts.

You should see: The rename is scheduled without an error, and Get-SPOTenantRenameStatus shows the job and its scheduled time.

The rename can take hours to days. Sites on the old domain are inaccessible until each one moves, so schedule it for a weekend or other quiet period.

Check the new onmicrosoft.com fallback domain

1. Open Settings > Domains in the Microsoft 365 admin center.
2. Confirm the new onmicrosoft.com domain is listed with a Healthy status.
3. Confirm the success message from step 2 named the new domain as your fallback domain.
4. Create a test user and confirm the new domain appears as the default in the Domains box.
5. If you scheduled a SharePoint rename, run Get-SPOTenantRenameStatus in a new PowerShell window and compare renamed sites with the total.
6. Check the Attention Required count; for failed sites, run Get-SPOSiteRenameState -ParentOperationID <RenameJobID> -State Failed.

Fallback onmicrosoft.com domain

Every Microsoft 365 tenant gets an onmicrosoft.com domain at sign-up, such as tailspintoys.onmicrosoft.com. It is a real domain that Microsoft owns and hosts for you.

Question	Answer
Where it is used by default	Usernames and email addresses, Microsoft 365 group and team email aliases, and automatic domain dependency moves
Email routing role	Keeps mail flowing to mailboxes if you remove a custom domain
SharePoint link	New SharePoint and OneDrive URLs use the original onmicrosoft.com name
Sending limit	From October 15, 2025, Microsoft began limiting onmicrosoft.com sending to 100 external recipients per 24 hours
Recommended use	Testing only; use a custom domain for regular email
Common reasons to change it	The company name was unknown or wrong at sign-up, or SharePoint URLs show an old name

SharePoint domain rename limits to check first

Limit	What it means
Site count	The standard rename supports up to 10,000 sites, OneDrive accounts and SharePoint Embedded containers combined; larger tenants need Advanced Tenant Rename in SharePoint Advanced Management
Number of renames	Two per tenant lifetime, with at least 30 days between them
Going back	Renaming back to the original name is not supported
Redirects	Old URLs redirect for one year after the rename
Blocked tenants	Multi-Geo, GCC, GCC High, DoD, .de tenants and vanity domains cannot rename
Email	The SharePoint rename does not change email addresses
Deleted sites	Sites deleted before the change cannot be restored afterwards, so restore any you need first
Power BI and workflows	Reports with SharePoint data sources and in-flight SharePoint 2013 workflows break and need reconnecting or republishing

Onmicrosoft domain troubleshooting

You cannot remove or delete an onmicrosoft.com domain

Microsoft does not allow onmicrosoft.com domains to be deleted once created.

1. Leave the unwanted domain in place.
2. Make the domain you do want the fallback domain under Settings > Domains.
3. Move users off the old domain with Manage username and email.

SharePoint and OneDrive URLs still show the old onmicrosoft name

A fallback domain change does not rename SharePoint.

1. Install the latest SharePoint Online Management Shell.
2. Connect with Connect-SPOService as a SharePoint Administrator.
3. Schedule the rename with Start-SPOTenantRename.
4. Track it with Get-SPOTenantRenameStatus.

"We're sorry, the user couldn't be edited" when changing a username

Your account is not in an admin role that can change usernames.

1. Ask a Global Administrator to assign you the User Administrator role.
2. Sign out and back in to the admin center.
3. Retry Manage username and email.

Start-SPOTenantRename is not found or returns nothing

An older SharePoint Online Management Shell is installed.

1. Run Uninstall-Module Microsoft.Online.SharePoint.PowerShell -Force -AllVersions.
2. Install the latest SharePoint Online Management Shell.
3. Reconnect with Connect-SPOService and run the command again.

Onmicrosoft domain FAQ

How do I change my onmicrosoft domain name?

You cannot rename it in place. In the Microsoft 365 admin center, go to Settings > Domains, select your onmicrosoft.com domain, choose Add onmicrosoft domain, then open the new domain and select Make fallback domain.

How do I create an onmicrosoft domain?

A Domain Name Administrator opens Settings > Domains, selects the existing onmicrosoft.com domain, chooses Add onmicrosoft domain, types a name and selects Add domain. A tenant can hold up to five onmicrosoft.com domains.

How do I add an onmicrosoft domain to my tenant?

Use the Add onmicrosoft domain link in the About this domain section of your current onmicrosoft.com domain. The Add domain button at the top of the Domains page adds a custom domain instead.

How do I remove an onmicrosoft domain?

You cannot. Microsoft does not allow onmicrosoft.com domains to be deleted once created. Make a different onmicrosoft.com domain the fallback and move users off the old one instead.

What is an onmicrosoft domain?

It is the free domain Microsoft gives every Microsoft 365 tenant at sign-up, such as contoso.onmicrosoft.com. It serves as the fallback domain for usernames, group aliases and email routing when you do not use your own domain.

Is onmicrosoft a domain?

Yes. onmicrosoft.com is a real domain owned by Microsoft, and each tenant gets its own subdomain of it. Microsoft provides it automatically, so you do not register it yourself.

What is a Microsoft domain email?

It is an address ending in yourname.onmicrosoft.com that Microsoft 365 assigns before you add your own domain. Microsoft recommends using it only for testing and limits its sending to external recipients.

How do I find my onmicrosoft domain?

Sign in to the Microsoft 365 admin center and open Settings > Domains. Your onmicrosoft.com domains are listed there, and a user's username under Users > Active users also shows the domain they sign in with.

Does changing the fallback domain change SharePoint URLs?

No. Existing SharePoint and OneDrive URLs keep the original name. Renaming them needs the Start-SPOTenantRename PowerShell cmdlet, which has its own limits, including two renames per tenant lifetime.

Does changing the onmicrosoft.com domain change email addresses?

Not for existing users. New users default to the new fallback domain, but you must edit existing usernames yourself. A SharePoint domain rename never changes email addresses.