How to Convert a User Mailbox to a Shared Mailbox in Office 365 (and Vice Versa)

Office 365 offers a wide range of benefits for businesses, and one of the most practical features is shared mailboxes. Shared mailboxes allow multiple users to access and manage email communications, and they come with built-in calendar functionalities for scheduling and sharing event information.

The best part? If the shared mailbox holds up to 50GB of data, you don’t need a license for it. However, for data exceeding 50GB, a license is required.

Why Convert a User Mailbox to a Shared Mailbox?

There are several scenarios where converting a regular user mailbox into a shared mailbox becomes necessary:

1. Collaborative Projects: If your team is working on a project that requires multiple people to access the same email data, converting the user mailbox into a shared one ensures everyone can stay on the same page.
2. Employee Departure: If an employee leaves the company, their email account might still hold valuable data. Converting their mailbox to a shared mailbox allows the business to retain access to that data while freeing up the user license.
3. Migration to Office 365: During a manual migration, such as a cutover or staged migration, user mailboxes are often converted to shared mailboxes. This allows the mailbox to remain active for 30 days without needing a license, helping businesses save costs.

Regardless of the scenario, converting a user mailbox to a shared one can provide operational benefits. Let’s walk through the process.

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How to Convert a User Mailbox to a Shared Mailbox in Office 365

Follow these steps to convert a regular mailbox to a shared mailbox in Office 365:

1. Log in to Office 365 with your global administrator credentials.
2. Click on the Admin option to access the Office 365 Admin Center.
3. In the admin window, go to Active Users and select the mailbox you want to convert.
4. Under Mail Settings, choose Convert to shared mailbox.
5. A confirmation prompt will appear. Click Convert to finalize the process.
6. Once complete, you’ll receive a message confirming the conversion. The mailbox will now be listed under Shared Mailboxes.

Important Note: If the shared mailbox exceeds 50GB, a license will be required. Additionally, ensure you disable sign-in for the shared mailbox to avoid security issues.

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Using Exchange Online PowerShell for Conversion

If you prefer or need to use Exchange Online PowerShell, you can also convert a user mailbox to a shared one via command line:

1. Connect to Exchange Online PowerShell with your administrator credentials. Use the following commands: $UserCredential = Get-Credential Enter your Office 365 admin credentials in the pop-up dialog.
2. Start the session: $Session = New-PSSession -ConfigurationName Microsoft.Exchange -ConnectionUri https://outlook.office365.com/powershell-liveid/ -Credential $UserCredential -Authentication Basic -AllowRedirection
3. Run the final command to import the session: Import-PSSession $Session -DisableNameChecking
4. Convert the mailbox: Set-Mailbox -Identity "user@example.com" -Type:Shared This command will convert the user mailbox to a shared mailbox.

If at any point you need to revert the shared mailbox back to a regular user mailbox, you can use the command: Set-Mailbox -Identity "user@example.com" -Type:Regular

How to Convert a Shared Mailbox Back to a User Mailbox

Occasionally, you may need to convert a shared mailbox back into a regular user mailbox. Here’s how to do it:

1. Log into Office 365 with admin credentials.
2. In the Office 365 Admin Center, navigate to Exchange under the admin options.
3. Go to the Recipients tab and select Shared mailboxes. Choose the shared mailbox you want to convert.
4. Under the Convert section, click Convert to user mailbox.
5. Confirm the conversion. The process may take some time, depending on the size of the mailbox.
6. Once complete, the mailbox will appear under the User Mailboxes section.

Note: After conversion, assign a license to the mailbox as it can only function without one for 30 days.

Final Words

Converting between user mailboxes and shared mailboxes in Office 365 is a straightforward process that can be completed using either the Office 365 Admin Center or PowerShell. Keep in mind the licensing requirements, especially if the shared mailbox exceeds 50GB of data.

For businesses concerned about data security, especially when migrating or managing large volumes of data, a professional Office 365 Backup tool can help safeguard mailboxes by storing data in PST format. This provides additional flexibility and peace of mind for future access.

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FAQs

1. Do shared mailboxes require a license in Office 365?
Shared mailboxes do not require a license as long as they hold less than 50GB of data. If the mailbox exceeds 50GB, a license is needed.

2. Can I convert a shared mailbox back to a user mailbox?
Yes, you can easily convert a shared mailbox back into a user mailbox using either the Office 365 Admin Center or PowerShell.

3. Will converting a user mailbox to shared affect email rules?
No, the existing email rules remain intact after conversion, though you should avoid making significant changes to the rules once converted.

4. What happens if I delete the user mailbox after conversion?
Do not delete the user mailbox after conversion, as it serves as an anchor for the shared mailbox to function correctly.

5. How do I backup a shared mailbox in Office 365?
You can use third-party tools like Office 365 to PST Converter software to securely back up shared mailboxes and store the data in PST format for future use.