How to Add Shared Mailbox with Same Email Name

You get an error message when creating a new shared mailbox in the Microsoft 365 admin center with the same email prefix (local part), even when you select different domains. This is because the name is already used, and it will also not let you add it for another domain. Learn how to add a shared mailbox with the same email name in a Microsoft 365 tenant.

Shared mailboxes in your Microsoft 365 tenant

You will get an error message in the Microsoft 365 admin center when creating a shared mailbox with the same email address name for another domain. That should not be the case, and there is a solution to bypass this problem.

In your Microsoft 365 tenant, you can have multiple domains. To check which domains you have, follow these steps:

1. Sign into Microsoft 365 admin center
2. Click Settings > Domains
3. See the list of domains

In our example, we have these:

• m365info.com
• ms365info.onmicrosoft.com (created by default)
• exoip.com

Check the shared mailboxes in the Microsoft 365 admin center, following these steps:

1. Sign into Microsoft 365 admin center
2. Click Teams & groups > Shared mailboxes
3. See the list of shared mailboxes

There is only one shared mailbox with the username info@m365info.com.

Email address not available because it’s used

Let’s add another shared mailbox in Microsoft 365 admin center following these steps:

1. Sign into Microsoft 365 admin center
2. Click Teams & groups > Shared mailboxes
3. Click Add a shared mailbox
4. Type the Name (Info EXOIP)
5. Type the same Email (info)
6. Select the Domains (exoip.com)

When you add the same shared mailbox email and select another domain in your Microsoft 365 tenant, you will get the error message below.

To bypass the error message, follow the steps below.

How to add shared mailbox with same email name

To add a shared mailbox with the same email name (local part) in Microsoft 365, follow the steps below.

Step 1. Add new shared mailbox in Microsoft 365

First, you must add a new shared mailbox in Microsoft 365 admin center:

1. Sign into Microsoft 365 admin center
2. Click Teams & groups > Shared mailboxes
3. Click Add a shared mailbox
4. Type the Name (Info EXOIP)
5. Type the Email (info1)
6. Select the Domains (exoip.com)
7. Click Save changes

8. Click on the new shared mailbox (info1@exoip.com)
9. Verify the new primary email address and alias

Step 2. Create same new shared mailbox email address

Change the properties for the new shared mailbox in Microsoft Entra ID:

1. Sign in to Microsoft Entra admin center
2. Click Identity > Users > All users
3. Search and click on the new shared mailbox (info1@exoip.com)

4. Click Edit properties

5. Click All
6. Change User principal name field

7. Change Email field
8. Change Mail nickname field
9. Click Save

You successfully changed the primary email address of the shared mailbox. The last step is to remove any alias addresses.

Step 3. Remove alias address

To remove the alias addresses of the shared mailbox in Microsoft 365 admin center, follow these steps:

1. Sign into Microsoft 365 admin center
2. Click Teams & groups > Shared mailboxes
3. Click on the shared mailbox
4. Click Edit

5. Click on the three dots next to the alias address
6. Select Delete alias
7. Repeat this for the other aliases

8. Click Save

9. It shows the new primary address (info@exoip.com) without any aliases

That’s it!

Read more: Manage Shared Mailbox with PowerShell »

Conclusion

You learned how to add a shared mailbox with the same email name in your Microsoft 365 tenant. To avoid the error message “email address is not available because it’s already used” you must go through the steps. First, create a new shared mailbox with a different email address for the other domain. Then, change the name and email address. Lastly, remove the aliases.

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