Forum Discussion

Matti Pekkarinen's avatar
Matti Pekkarinen
Copper Contributor
Sep 20, 2018

Shared mailbox with the same email (local part) can't be created to a different domain

Hello everyone,

 

I have a shared mailbox support@domain1.com.

 

The problem: When I'm trying to create a shared mailbox support@domain2.com this results in an error saying that each mailbox should have unique name and that this name is already in use.

I have verified both domains an set up dns correctly. Doesn't O365 separate email addresses from different domains even if they have the same local part (support)?

Is it even possible to have the same local part for emails from two domains?

I need an email address for support for all of my domains and since I'm migrating from another service, they all must be in the form support@domain.com.

Thank you in advance for your input, Matti

  • Moi Matti,

     

    The problem is that when you create a shared mailbox, the alias with the local name is also created. Thus, regardless of the domain part, you have the error you described.

     

    Luckily the workaround is quite simple. Just create a shared mailbox with unique local name, such as support_domain2@domain2.com. After it is created, edit the mailbox email addresses to change the default address to support@domain2.com and you're done!

  • JoshLenz's avatar
    JoshLenz
    Copper Contributor

    Matti Pekkarinen 

     

    Hi Matt,

     

    So I think i found out how to do it but its a bit of a workaround. Though this may be wayyyy too late but in case someone else out there is like me...

    In summary : You can create a normal user account and then convert it to a shared mailbox.

     

    Note that the spaces between addresses are actually full stops '.'

    Scenario:

    I have User: John with User account:

    john @ domain1 com already in the system

    I want a shared mailbox called John @ domain2 com

    I also have domain1 .onmicrosoft com (which have had from the start)

     

    To create a user with the same alias but a different domain I needed at least 3 different domains to choose from in the drop down as 365 seems to create an alias with the same name in the previously selected drop down domain. So I go to create a user account for Johns shared mailbox (aka second domain account). The drop down however is already populated with @Domain1 com. So I enter his name and I change the dropdown to Domain1 . onmicrosoft com. Its like Nahhh cause there already is an alias in the system with @domain1 com. Thats fine now I change to @Domain2 com and as there is no account in the system with John @ Domain1 onmicrosoft com so it lets me do it. Once the account is created is creates an alias with an @onmicrosoft com address for that account (this can be deleted if you want)

     

    I hope this makes sense and works for someone else too.

     

    Have a great day

     

    Josh

     

     

  • Moi Matti,

     

    The problem is that when you create a shared mailbox, the alias with the local name is also created. Thus, regardless of the domain part, you have the error you described.

     

    Luckily the workaround is quite simple. Just create a shared mailbox with unique local name, such as support_domain2@domain2.com. After it is created, edit the mailbox email addresses to change the default address to support@domain2.com and you're done!

    • Matti Pekkarinen's avatar
      Matti Pekkarinen
      Copper Contributor
      Seems like a similar problem. The linked post is quite old though.

      I have no idea how to replicate the solution in office 365 admin center.
      • VasilMichev's avatar
        VasilMichev
        MVP

        Simply use PowerShell, the UI is limited for this scenario.

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