Here's how you can convert a shared mailbox into a user mailbox

For Microsoft 365, shared mailboxes can be converted back to user mailboxes. If you need to access the mailbox directly (from an application or specific device) or accidentally convert the wrong mailbox to a shared mailbox, this can be necessary.

User mailboxes require a licence at all times. It can either be a Microsoft 365 plan that includes Exchange Online or an Exchange Online-only plan. The mailbox cannot be accessed without a licence.

Shared mailboxes can be converted to user mailboxes

The shared mailbox can be converted in two ways. PowerShell or Exchange Admin Centre can be used. First, let's look at the Exchange Admin Centre.

In the Exchange Admin Centre, shared mailboxes are listed alongside normal mailboxes. To display only shared mailboxes, either search for the shared mailbox name in the list or use the filter:

Now that the shared mailboxes are listed, let's change the mailbox back to the user mailbox:

1. Open the shared mailbox in the Exchange Admin Centre
2. The tab Other can be found by clicking on it
3. Choose Convert to a regular mailbox from the menu
4. Confirm the prompt by clicking Confirm

In the mailboxes list, the mailbox should now appear as a UserMailbox. You won't be able to access the mailbox unless you assign an appropriate licence to the user.

Convert a shared mailbox to a user mailbox using PowerShell

PowerShell can also be used to convert a shared mailbox back to a user mailbox. PowerShell must be installed with the Exchange Online module.

The Set-Mailbox cmdlet is used to convert the mailbox back. Identity is determined by the mailbox's email address. You can also use the mailbox name, but the email address is more unique, so it is a better choice.

Note the type is set to Regular and not User.

# Connect to Exchange Online
Connect-ExchangeOnline -UserPrincipalName admin@dynamicstech.onmicrosoft.com
# Convert Shared mailbox back to user
Set-Mailbox -Identity james@dynamicstech.onmicrosoft.com -Type Regular

There is no output or indication that the operation has succeeded when the cmdlet is run. You will only be notified if there is an error. The Get-Mailbox cmdlet can be used to determine if the mailbox has been converted to a regular mailbox:

Get-Mailbox -Identity james@dynamicstech.onmicrosoft.com | Select Name, RecipientTypeDetails

# Result
Name        RecipientTypeDetails
----        --------------------
james-test UserMailbox

You can see the mailbox type has been changed to usermailbox. To access the mailbox, ensure the user account has an appropriate licence.