Hi Everyone this is Prem, I have worked as Microsoft 365 Support Ambassador. We saw a lot of ticket for “ Not able to Create Users with the Same Name and Different Domain in Office 365”.
In this blog I am going to share a common step which we used to suggest to end users.
When we create a user with the same name and different domain we get the error that the email address is already been used, this is because of the default domain setup.
When we create a user, a secondary email address gets added as a alias for the account, if you have your domain.onmicrosoft.com set as default domain it will create an alias with it.
This mostly happens when we create shared mailbox on different domains with the same name.
For example: If I create a user with the email address ABC@domain1.com and I want to create a new account for the same user but on a different domain like ABC@domain2.com.
It will not allow me to do so, as the default domain’s alias gets added the first time you create the user.
So for ABC@domain1.com it created ABC@domain.onmicrosoft.com(Depends on the default domain you have set) and when you try to create ABC@domain2.com it fails to create ABC@domain.onmicrosoft.com as it has already been used.
Fix Create Users with the Same Name and Different Domain:
When creating the user account for the second time, use a different alias so that the alias with the default domain can be created without any issue.
Then you can later edit the email address/user principal name.
For eg: To create the second account for the user with email address ABC@domain2.com, I will use ABC1@domain2.com instead.
This will create an alias of ABC1@domain.onmicrosoft.com in the backend.
Once the user gets created successfully we can go ahead and change the email address of the account to the one which we wanted, that is ABC@domain2.com.
This is the steps which we use for this issue, do let us know if this helped you to fix the issue.
Tags: Create Users with the Same Name and Different Domain