Manage inactive mailboxes in Exchange Online
Applies to: Exchange Online
Topic Last Modified: 2014-10-03
Exchange Online makes it possible for you to preserve the contents of deleted mailboxes indefinitely. This feature is called inactive mailboxes. A mailbox becomes inactive when an In-Place Hold or a Litigation Hold is placed on the mailbox before the corresponding Office 365 user account is deleted. The contents of an inactive mailbox are preserved indefinitely. This allows administrators, compliance officers, or records managers to use the In-Place eDiscovery feature in Exchange Online to access and search the contents of an inactive mailbox. Inactive mailboxes can't receive email and aren't displayed in your organization's shared address book or other lists.
|If a hold isn't placed on a mailbox before it's deleted, the contents of the mailbox won't be preserved or discoverable. The mailbox can be recovered within 30 days of deletion, but the mailbox and its contents will be permanently deleted after 30 days if it isn't recovered.|
The license associated with the deleted Exchange Online mailbox will be available after you delete the mailbox. You can then assign that license to another user.
Estimated time to complete each procedure: Less than 5 minutes.
To make a mailbox inactive, it must be assigned an Exchange Online (Plan 2) license so that an In-Place Hold or a Litigation Hold can be placed on the mailbox before it's deleted. If a mailbox is assigned an Exchange Online (Plan 1) license, you have to assign it a separate Exchange Online Archiving license so that a hold can be placed on the mailbox before it's deleted. For more information, see:
For information about keyboard shortcuts that may apply to the procedures in this topic, see Keyboard shortcuts in the Exchange admin center.
Making a mailbox inactive involves two steps: placing the mailbox on In-Place Hold or Litigation Hold and then deleting the mailbox or corresponding Office 365 user account. After the mailbox is inactive, its contents are preserved until the hold is removed.
Placing a mailbox on In-Place Hold preserves all contents that were in the mailbox before it was deleted. You can place the mailbox on indefinite hold or on a time-based hold. In an indefinite hold, the inactive mailbox and all its contents will be preserved until the hold is removed. After the hold is removed (assuming that the mailbox was deleted more than 30 days ago), the inactive mailbox will be permanently deleted and the contents of the mailbox will no longer be preserved or discoverable. In a time-based hold, you specify the duration of the hold. This duration is on a per-item basis and is calculated from the date a mailbox item was received or created. After the hold expires for a mailbox item, the item is permanently deleted from the inactive mailbox.
As previously described, the mailbox must be assigned an Exchange Online (Plan 2) license or have an Exchange Online Archiving subscription so that an In-Place Hold can be placed on the mailbox.
For step-by-step procedures for placing a mailbox on In-Place Hold, see Create or remove an In-Place Hold.
Placing a mailbox on Litigation Hold also preserves all mailbox content, including deleted items and original versions of modified items. Deleted and modified items are preserved for a specified period, or until you remove the mailbox from Litigation Hold. All such mailbox items are returned in an In-Place eDiscovery search. For step-by-step procedures, see Place a mailbox on Litigation Hold.
After the mailbox is placed on hold to preserve its contents, it can be deleted. The best way to delete a mailbox is to delete the corresponding Office 365 user account in the Office 365 admin center. For information about deleting Office 365 user accounts, see Delete or restore users.
|You can also delete the mailbox by using the Remove-Mailbox cmdlet in the Exchange Management Shell.|
After you make a mailbox inactive by placing the mailbox on hold and then deleting the corresponding Office 365 user account, you can access the contents of the inactive mailbox by using In-Place eDiscovery in the Exchange admin center (EAC). When you search an inactive mailbox, you can create a keyword search query to search for specific items or you can return the entire contents of the inactive mailbox. You can preview the search results, copy the search results to a discovery mailbox, or export the search results to an Outlook Data (PST) file. For step-by-step procedures for searching mailboxes, see Create an In-Place eDiscovery search.
If you no longer need to preserve the contents of an inactive mailbox, you can permanently delete the inactive mailbox by removing the hold. If the mailbox was deleted more than 30 days ago, the mailbox will be permanently deleted after you remove the hold, and mailbox items will become non-recoverable. If the mailbox was deleted within the last 30 days, you can still restore the mailbox after removing the hold.
For step-by-step procedures for removing hold, see: