At some point, you may want to convert a user mailbox to a shared mailbox. Perhaps as part of your Office 365 mailbox life cycle management when a user leaves your organization.
This post will show how to convert an Office 365 mailbox to a shared mailbox using the Set-Mailbox PowerShell command.
You’ll also see how to do it via the Active Directory Users & Computers management console and the Exchange Admin Center.
Mailbox Conversion Using PowerShell
Use the Set-Mailbox PowerShell command to convert your Office 365 mailbox to a shared mailbox. The below example shows you how:
Connect-ExchangeOnline
Set-Mailbox username@company.com -Type Shared
Disconnect-ExchangeOnline
Start by establishing a connection with Exchange Online (lines 1 – 3).
Convert the mailbox type using the Set-Mailbox command (line 4).
End your Exchange Online session when done (line 5). If you don’t explicitly close the session, you risk depleting the number of available sessions.
To convert your mailbox to other types than Shared, use these parameters: Regular (user), Room, and Equipment.
To verify the conversion, take a look at the RecipientTypeDetails of the mailbox:
PS C:\WINDOWS\system32> Get-Mailbox Marketing | fl Name,RecipientTypeDetails Name : Marketing RecipientTypeDetails : SharedMailbox
License Considerations
A shared mailbox in Office 365 does not require a license, but you need to have your own personal mailbox (which must be licensed) to access it. Also, if you want your shared mailbox to store more than 50 GB or to have an archive, you need to license it.
Keep in mind that you shouldn’t delete the user account after converting the mailbox to a shared mailbox. The user account is still needed, although you can’t use it for logging in.
Mailbox Conversion Using Active Directory Users & Computers
Another option to perform the mailbox conversion is using the Active Directory Users & Computers MMC.
You need to have the Easy365Manager snapin installed to follow this procedure.
Open up user properties and go to the Mailbox tab. Here you can select any of the four mailbox types to convert the mailbox:

After converting the mailbox to a shared mailbox, you can remove the license. You can also do this using the Easy365Manager tool, as seen in the following screenshot:

Alternatively, you can use the Office 365 Admin Portal to remove the Exchange Online license.
Easy 365Manager can make your admin life a lot easier. Stop switching between multiple admin tools throughout the day. Manage all AD user and email configurations, Office 365 mailboxes and Office 365 licenses from AD Users & Computers.
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You can discover more Easy365Manager features here.
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Mailbox Conversion Using the Exchange Admin Center
You can also perform mailbox type conversion using the Exchange Admin Center. To change the mailbox type, follow these steps:
Open up the Exchange Admin Center using your admin account and locate the mailbox you want to convert:

Clicking “Convert” will generate a warning and clicking Yes will start the mailbox conversion:
