Cannot add a domain to a new tenant since it seems to exist already in Office 365?

[DanHuber]

I need to add a domain to a new tenant (i.e. tenantname.onmicrosoft.com, where "tenantname is equivalent to the domainname without the TLD. I use "tenantname.com" as a placeholder here).

The Office 365 Admin center tells me that the domain (i.e. tenantname.com) needs to be removed from another account. It says:

"The domain could not be added to your accoint because another person has already used an email address that ends with "tenantname.com" and registred for Office 365"

(or similar, I translate from German)

I have no clue who is that and what is the person.

The domain "tenantname.com" is clearly ours. 

What are the steps to get the domainname onto the the tenant?

How do I find out which other tenant does hold the domainname in question?

Thanks

Dan

[#2]

Unfortunately, I had to ask this before, the answer was: "If you don't know which Office 365 account is currently using the custom domain, or if you don't have control over the Office 365 account that the custom domain is currently using, contact Office 365 support."

Good Luck

[#3]

@DanHuber 

May check the Domain owner by who is

[#4]

Well, I am the domain owner

[#5]

Yeah.. I did that... They started with a huge paperwork thingy...

[#6 · Accepted solution]

Thanks for all who responded.
I got the thing working.

I only had the hint of a******@tenantname.com for something called "Account Takeover"...
So I created aliases that made sense for me starting with "a"..

The 5th attempt was successful and I got an email with a link. From there it was simple. I got the login to a tenant that was called something like "tenantnamecom.onmcrosoft.com" with the login of email address removed for privacy reasons. As it turned out, someone started that process, but stopped in the middle. So the domain "tenantname.com" was kind of reserved for Office 365, but not actually finalized the setup.

After I finalized the setup, I changed the loginname of email address removed for privacy reasons to email address removed for privacy reasons, logged of, logged in again with the new name. Then removed the domain "tenantname.com" from that tenant "tenantnamecom".

After that, I was able to add tenantname.com to my own tenant.. The tenant "tenantnamecom" now sits around idling for itself until it will be probably removed by Microsoft.

I only assume that the whole thing was a leftover from the change of the VLA login procedures..


Perhaps those hints might help someone lese in the future.

Dan