Shared Mailbox multiple domains

Copper Contributor

I've got 3 unique domains that each currently have their own admin@ account. I want to manage all three domains on one tenant, but I cant seem to have multiple shared mailboxes with the same prefix ie:


The user who monitors these mailboxes needs to be able to send uniquely from all of those domains. Is this possible?

3 Replies

You can, simply don't use the Admin center to create them - it tries to enforce uniqueness of the "alias" and forgets to check the different domain name. Use PowerShell to create them, or simply create them with different alias and change it later.

What would the commands be to set them up in Powershell? 

I tried to set them up uniquely in Exchange Admin, and then change them after but it failed, it still wasn't looking at the domain. 

It's simple:


New-Mailbox -Name Shared1 -Shared -PrimarySmtpAddress


If needed, also use the -Alias parameter.