Can’t add a domain to Office 365 because it’s already in use

Adding a domain name to Office 365 is usually pretty straightforward. That is unless it’s already been used for another tenant that you don’t have access to – perhaps a trial that’s expired? Or someone signed up for some Microsoft Online services using their work email address but doesn’t have administration rights?

I came across exactly this scenario with a customer last week – although luckily we managed to extract ourselves from the situation. Actually, there’s some pretty good documentation from Microsoft on the topic: “How to manage a domain already in use by people in your organization who signed up with their work or school email address“.

What we did was to:

• Sign up for a Power BI trial (we couldn’t sign up for Office Online at work as it said it wasn’t available in our region, and Office 365 for education was not an option for us either) using an email address at the domain name we wanted to reclaim.
• Once the new trial was in place, logon to the portal and click the Admin tile in the App Launcher, which starts a wizard to become the administrator for the associated Office 365 tenant.
• Create a DNS entry to prove ownership of the domain.
• Change any account using the domain name that is to be reclaimed over to their tenantname.onmicrosoft.com address for logon.
• Log off/on.
• Remove the domain from the tenant (and then leave it to expire in time…).
• Add the domain to the tenant where it should be used.