Manage inactive mailboxes in Exchange Online
Applies to: Exchange Online, Office 365
Topic Last Modified: 2016-06-09
Exchange Online makes it possible for you to preserve the contents of deleted mailboxes. This feature is called inactive mailboxes. Inactive mailboxes allow you to preserve former employees’ email after they leave your organization. A mailbox becomes inactive when a Litigation Hold or an In-Place Hold is placed on the mailbox before the corresponding Office 365 user account is deleted. The contents of an inactive mailbox are preserved for the duration of the hold that was placed on the mailbox before it was made inactive. This allows administrators, compliance officers, or records managers to use In-Place eDiscovery 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 deleted 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.|
To make a mailbox inactive, it must be assigned an Exchange Online (Plan 2) license so that a Litigation Hold or an In-Place Hold can be placed on the mailbox before it's deleted. Exchange Online (Plan 2) licenses are part of an Office 365 365 Enterprise E3 and E5 subscriptions. If a mailbox is assigned an Exchange Online (Plan 1) license (which is part of an Office 365 365 Enterprise E1 subscription), you would 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 Exchange Online Archiving.
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.
For more information about holds, see In-Place Hold and Litigation Hold.
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 or Litigation Hold preserves all contents in the mailbox before it's deleted. Both types of holds will preserve all mailbox content, including deleted items and original versions of modified items. Deleted and modified items are preserved in the inactive mailbox for a specified period, or until you remove the mailbox from hold.
For step-by-step procedures for placing a mailbox on hold, see:
|For In-Place Hold and Litigation Hold, you can place the mailbox on indefinite hold or on a time-based hold. In an indefinite hold, the contents of the inactive mailbox will be preserved until the hold is removed or the hold duration is changed. After the hold is removed (assuming that the mailbox was deleted more than 30 days ago), the inactive mailbox will be marked for permanent deletion 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, and that item is located in the Recoverable Items folder in the inactive mailbox, the item is permanently deleted (purged) from the inactive mailbox.|
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 Windows PowerShell. For more information, see Delete or restore user mailboxes in Exchange Online.|
The following sections describe what you can do after you make a mailbox inactive.
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.
After a mailbox is made inactive, you can change the duration of the Litigation Hold or the In-Place Hold on the inactive mailbox. For step-by-step procedures, see Change the hold duration for an inactive mailbox in Exchange Online.
If a departed employee returns to your organization, or if a new employee is hired to take on the job responsibilities of the departed employee, you can recover the contents of the inactive mailbox. When you recover an inactive mailbox, the mailbox is converted to a new mailbox, the contents and folder structure of the inactive mailbox are retained, and the mailbox is linked to a new user account. After it's recovered, the inactive mailbox no longer exists. For step-by-step procedures and more information about happens when you recover an inactive mailbox, see Recover an inactive mailbox in Exchange Online.
If another employee takes on the job responsibilities of the departed employee, or if another person needs access to the contents of the inactive mailbox, you can restore (or merge) the contents of the inactive mailbox to an existing mailbox. When you restore an inactive mailbox, the contents are copied to another mailbox. The inactive mailbox is preserved and remains an inactive mailbox. The inactive mailbox can still be searched using eDiscovery, its contents can be restored to another mailbox, or it can be recovered or deleted at a later date. For step-by-step procedures, see Restore an inactive mailbox in Exchange Online.
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 marked for permanent deletion after you remove the hold, and the mailbox will become non-recoverable. If the mailbox was deleted within the last 30 days, you can still recover the mailbox after removing the hold. For step-by-step procedures for removing a hold to permanently delete an inactive mailbox, see Remove a hold from an inactive mailbox in Exchange Online.