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Archiving a Terminated Users Mailbox in Office 365 using Inactive Mailboxes

Jun 6, 2014 by Emma Robinson

Microsoft have now added a feature that allows you to keep a terminated employee mailbox on your Office 365 cloud environment even after you have deleted their user account and freed up their license. This feature is called Inactive Mailboxes.

We do not charge you for these kinds of Inactive Mailboxes in our Office 365 management tool, so it’s a win-win!

This is a great way to ensure that their mailbox content is preserved in the event that you need to recover some of their mail later on. The mailbox can remain on Office 365 indefinitely without any cost to your company. Unfortunately, it requires you to be using an Enterprise version of Office 365.

Read more Optimizing PowerShell for large Office 365 tenants

To do this you will need to follow these steps:

  1. Assign an Exchange Online (Plan 2) license or an Exchange Online Archiving subscription to the user so that an In-Place Hold can be placed on the mailbox.  Note: You only need one of these licences and it is only used temporarily. Once the mailbox has been marked as Inactive you can free up the licence and use it again to do the next one.
  2. Log in to the Office 365 Admin center and go to the Exchange Admin Center
  3. Click Compliance Management on the left hand side and In Place eDiscovery and Hold at the top
Terminated Users In-Place Hold

Terminated Users In-Place Hold

4. Create a new In-Place Hold Policy and call it Terminated Employees

5. Add the terminated user to the policy

6. Ensure that All Mailbox Content is preserved

7. Tick the box to enable the hold

8. You should now see the user on hold in the recipients section


In-Place Hold Enabled

In-Place Hold Enabled

9. Delete the Users Account from the Office 365 Administrator center. The mailbox is now deemed “Inactive” and the licence can be re-assigned


Delete User

Delete User

To view a list of all your Inactive Mailboxes in Office 365 you can use the following PowerShell cmdlet
PS C:\Users\alan\Desktop> Get-Mailbox -InactiveMailboxOnly
Name Alias ServerName ProhibitSendQuota
---- ----- ---------- -----------------
DavidL DavidL am3pr07mb0534 49.5 GB

Use an In-Place eDiscovery search to access the contents of the mailbox.

Read more Optimizing PowerShell for large Office 365 tenants

You can easily view a list of all your Inactive Mailboxes using our Inactive Mailbox Report.