Our email domain is associated with a tenant we don't have access to - help please

[45support]

We are in the process of moving from on-premise Exchange to Exchange Online. We already have a tenant owned by our company and everyone has a subscription to Office 365 applications. The problem is now when we try to associate our current email domain to the existing tenant, a message says we can't because that email domain is associated with another tenant. We need to remove our email domain from that tenant first in order to associate it with the tenant we own.

The problem is that the tenant our email domain is currently associated with is not one anyone is familiar with or has access to. The password reset function indicates we don't have the ability to perform a password reset. So how on earth do we get our domain deleted off from this tenant?

Thanks in advance.

[#2]

Try the "takeover" methods outlined here: https://docs.microsoft.com/en-us/azure/active-directory/enterprise-users/domains-admin-takeover
If those cannot help, open a support case and work with the engineer to verify ownership.

[#3]

@Vasil Michev 

Thanks. I have tried both the internal and external takeover options, and both fail. What's the best way to open a case with Microsoft?

[#4]

Call them: https://support.office.com/en-us/article/Contact-Office-365-for-business-support-32a17ca7-6fa0-4870-...