Cannot create shared mailbox

Question

Cannot create a shared mailbox, error message says Email is in use.

Answer 1

Hello Andrew Mike,

Thank you for reaching out.

To better assist you, I’d like to gather some additional details to pinpoint the root cause of the "Email is in use" error.

1. Creation Method:
   • Are you using the Microsoft 365 Admin Center, Exchange Admin Center (EAC), or PowerShell to create the shared mailbox?
2. Previous Usage of the Email Address:
   • Has this email address ever been assigned to a user, another shared mailbox, or a distribution group in the past?
   • If yes, was the previous object deleted? (If so, it may still exist in a soft-deleted state.)
3. Existing Conflicts:
   • Could you check if the email address is already in use by another object (e.g., a mail-enabled security group, contact, or dynamic distribution list)?
   • You can verify this in the Exchange Admin Center (EAC):
     • Navigate to Recipients > Shared Mailboxes / Groups / Contacts and search for the address.
4. Hybrid Environment (if applicable):
   • Is your organization using a hybrid Exchange setup (on-premises + Exchange Online)?
   • If yes, the address may still exist in on-premises Active Directory and needs to be cleaned up before it can be reused.

Next Steps You Can Try:

• Check for Soft-Deleted Mailboxes (if previously used):
  • In Exchange Admin Center > Recipients > Deleted Mailboxes, look for the mailbox.
  • If found, you may need to restore or permanently purge it before reusing the address.
• PowerShell Check (for Admins):
  Run the following command in Exchange Online PowerShell to check for conflicts:

powershell

    Get-Recipient "******@domain.com" | fl Name, RecipientType, RecipientTypeDetails

If the address is tied to a deleted mailbox, you need to remove it.

Once I have these details, I’ll be able to guide you through the next steps!

Looking forward to your response.