custom domain issue

Question

Hi, I've discovered that my domain has been registered to a different Microsoft 365 tenant, which is preventing me from verifying it—even though I am the rightful owner. I understand there are tools that can identify the tenant ID currently associated with the domain, but resolving this issue requires Microsoft’s intervention.

Could someone from Microsoft please assist me in reclaiming my domain? I can provide documentation to verify ownership if needed.

Thank you for your support.

Answer 1

The association between a domain name and tenant ID is publicly available.

The quickest way to find out is to use this link.

https://login.microsoftonline.com/microsoft.com/FederationMetadata/2007-06/FederationMetadata.xml

This shows that the tenant ID of microsoft.com is 72f988bf-86f1-41af-91ab-2d7cd011db47 (on the top line under entityID).

So just change the URL to include your domain name instead of microsoft.com, and that will tell you the tenant ID that owns your domain.

There are also programmatic ways to do this through the graph API, but for your purposes the above metadata link should be fine. https://learn.microsoft.com/en-us/graph/api/tenantrelationship-findtenantinformationbydomainname?view=graph-rest-1.0&tabs=http

What can sometimes happen is that a user could set up a viral trial tenant and if they have DNS access could add a verified domain. See if this link helps you if that is what happened, as it may be possible to fix it yourself without Microsoft's help. https://learn.microsoft.com/en-us/entra/identity/users/domains-admin-takeover

If that doesn't help, I suggest you open a support ticket through the M365 admin centre of the tenant you can access.