Change the hold duration for an inactive mailbox

An inactive mailbox is used to retain a former employee's email after he or she leaves your organization. A mailbox becomes inactive when a Litigation Hold, an In-Place Hold, a Microsoft 365 retention policy, or a hold that's associated with an eDiscovery case is placed on the mailbox, and the corresponding user account is deleted. The contents of an inactive mailbox are retained for the duration of the hold that was placed on the mailbox before it was made inactive. The hold duration defines how long items in the Recoverable Items folder are held. When the hold duration expires for an item in the Recoverable Items folder, the item is permanently deleted (purged) from the inactive mailbox. After a mailbox is made inactive, you can change the duration of the hold or Microsoft 365 retention policy assigned to the inactive mailbox.

Important

As we continue to invest in different ways to preserve mailbox content, we're announcing the retirement of In-Place Holds in the Exchange admin center. That means you should use Litigation Holds and Microsoft 365 retention policies to create an inactive mailbox. Starting April 1, 2020 you won't be able to create new In-Place Holds in Exchange Online. But you'll still be able to change the hold duration of an In-Place Hold placed on an inactive mailbox. However, starting July 1, 2020, you won't be able to change the hold duration. You'll only be able to delete an inactive mailbox by removing the In-Place Hold. Existing inactive mailboxes that are on In-Place Hold will still be preserved until the hold is removed. For more information about the retirement of In-Place Holds, see Retirement of legacy eDiscovery tools.

Connect to PowerShell

  • You have to use Exchange Online PowerShell to change the hold duration for a Litigation Hold on an inactive mailbox. You can't use the Exchange admin center (EAC). But you can use Exchange Online PowerShell or the EAC to change the hold duration for an In-Place Hold. You can use the security and compliance center or Security & Compliance Center PowerShell to change the hold duration for a Microsoft 365 retention policy.

  • To connect to Exchange Online PowerShell or Security & Compliance Center PowerShell, see one of the following topics:

  • Holds associated with eDiscovery cases are infinite holds, which means there's no hold duration that can be changed. Items are held forever or until the hold is removed and the inactive mailbox is deleted.

  • For more information about inactive mailboxes, see Inactive mailboxes in Microsoft 365.

Step 1: Identify the holds on an inactive mailbox

Because different types of holds or one or more Microsoft 365 retention policies might be placed on an inactive mailbox, the first step is to identify the holds on an inactive mailbox.

Run the following command in Exchange Online PowerShell to display the hold information for all inactive mailboxes in your organization.

Get-Mailbox -InactiveMailboxOnly | FL DisplayName,Name,IsInactiveMailbox,LitigationHoldEnabled,LitigationHoldDuration,InPlaceHolds

The value of True for the LitigationHoldEnabled property indicates that the inactive mailbox is on Litigation Hold. If an In-Place Hold, eDiscovery hold, or Microsoft 365 retention policy is placed on an inactive mailbox, a GUID for the hold or retention policy is displayed as the value for the InPlaceHolds property. For example, the following shows results for five inactive mailboxes.

DisplayName           : Ann Beebe
Name                  : annb
IsInactiveMailbox     : True
LitigationHoldEnabled : True
LitigationHoldDuration: 365.00:00:00
InPlaceHolds          : {}
...
DisplayName           : Pilar Pinilla
Name                  : pilarp
IsInactiveMailbox     : True
LitigationHoldEnabled : False
LitigationHoldDuration: Unlimited
InPlaceHolds          : {c0ba3ce811b6432a8751430937152491}
...
DisplayName           : Mario Necaise
Name                  : marion
IsInactiveMailbox     : True
LitigationHoldEnabled : False
LitigationHoldDuration: Unlimited
InPlaceHolds          : {}
...
DisplayName           : Carol Olson
Name                  : carolo
IsInactiveMailbox     : True
LitigationHoldEnabled : False
LitigationHoldDuration: Unlimited
InPlaceHolds          : {mbxcdbbb86ce60342489bff371876e7f224}
...
DisplayName           : Abraham McMahon
Name                  : abrahamm
IsInactiveMailbox     : True
LitigationHoldEnabled : False
LitigationHoldDuration: Unlimited
InPlaceHolds          : {UniH7d895d48-7e23-4a8d-8346-533c3beac15d}

The following table identifies the five different hold types that were used to make each mailbox inactive.

Inactive mailbox Hold type How to identify the hold on the inactive mailbox
Ann Beebe
Litigation Hold
The LitigationHoldEnabled property is set to True.
Pilar Pinilla
In-Place Hold
The InPlaceHolds property contains the GUID of the In-Place Hold that's placed on the inactive mailbox. You can tell this is an In-Place Hold because the ID doesn't start with a prefix.
You can use the Get-MailboxSearch -InPlaceHoldIdentity <hold GUID> | FL command in Exchange Online PowerShell to get information about the In-Place Hold on the inactive mailbox.
Mario Necaise
Organization-wide Microsoft 365 retention policy in the Microsoft 365 compliance center
The InPlaceHolds property is empty. This indicates that one or more organization-wide or (Exchange-wide) Microsoft 365 retention policy is applied to the inactive mailbox. In this case, you can run the Get-OrganizationConfig | Select-Object -ExpandProperty InPlaceHolds command in Exchange Online PowerShell to get a list of the GUIDs for organization-wide Microsoft 365 retention policies. The GUID for organization-wide retention policies that are applied to Exchange mailboxes start with the mbx prefix; for example, mbxa3056bb15562480fadb46ce523ff7b02.

To identity the Microsoft 365 retention policy that's applied to the inactive mailbox, run the following command in Security & Compliance Center PowerShell.

Get-RetentionCompliancePolicy <retention policy GUID without prefix> | FL Name

Carol Olson
Microsoft 365 retention policy in the Microsoft 365 compliance center applied to specific mailboxes
The InPlaceHolds property contains the GUID of the Microsoft 365 retention policy that's applied to the inactive mailbox. You can tell this is a retention policy that applied to specific mailboxes because the GUID starts with the mbx prefix. If the GUID of the retention policy applied to the inactive mailbox started with the skp prefix, it would indicate that the retention policy is applied to Skype for Business conversations.

To identity the Microsoft 365 retention policy that's applied to the inactive mailbox, run the following command in Security & Compliance Center PowerShell.

Get-RetentionCompliancePolicy <retention policy GUID without prefix> | FL Name

Be sure to remove the mbx or skp prefix when you run this command.
Abraham McMahon
eDiscovery case hold in the Microsoft 365 compliance center
The InPlaceHolds property contains the GUID of the eDiscovery case hold that's placed on the inactive mailbox. You can tell this is an eDiscovery case hold because the GUID starts with the UniH prefix.
You can use the Get-CaseHoldPolicy cmdlet in Security & Compliance Center PowerShell to get information about the eDiscovery case that the hold on the inactive mailbox is associated with. For example, you can run the command Get-CaseHoldPolicy <hold GUID without prefix> | FL Name to display the name of the case hold that's on the inactive mailbox. Be sure to remove the UniH prefix when you run this command.

To identity the eDiscovery case that the hold on the inactive mailbox is associated with, run the following commands.

$CaseHold = Get-CaseHoldPolicy <hold GUID without prefix>

Get-ComplianceCase $CaseHold.CaseId | FL Name


Note: We don't recommend using eDiscovery holds for inactive mailboxes. That's because eDiscovery cases are intended for specific, time-bound cases related to a legal issue. At some point, a legal case will probably end and the holds associated with the case will be removed and the eDiscovery case will be closed (or deleted). In fact, if a hold that's placed on an inactive mailbox is associated with an eDiscovery case, and the hold is released or the eDiscovery case is closed or deleted, the inactive mailbox will be permanently deleted.

For more information about Microsoft 365 retention policies, see Learn about retention policies and retention labels.

Step 2: Change the hold duration for an inactive mailbox

After you identify what type of hold is placed on the inactive mailbox (and whether there are multiple holds), the next step is to change the duration for the hold.

Change the duration for a Litigation Hold

Here's how to use Exchange Online PowerShell to change the hold duration for a Litigation Hold that is placed on an inactive mailbox. You can't use the EAC. Run the following command to change the hold duration. In this example, the hold duration is changed to an unlimited period of time.

Set-Mailbox -InactiveMailbox -Identity <identity of inactive mailbox> -LitigationHoldDuration unlimited

The result is that items in the inactive mailbox are retained indefinitely or until the hold is removed or the hold duration is changed to a different value.

Tip

The best way to identify an inactive mailbox is by using its Distinguished Name or Exchange GUID value. Using one of these values helps prevent accidentally specifying the wrong mailbox.

Change the duration for an In-Place Hold

In-Place Holds have been retired and can no longer be modified. If an inactive mailbox has an In-Place Hold applied to it, you can't change the hold duration. You can only remove the In-Place Hold, which will result in the deletion of the inactive mailbox. For more information, see Delete an inactive mailbox.

More information

  • How is the hold duration calculated for an item in an inactive mailbox? The duration is calculated from the original date a mailbox item was received or created.

  • What happens when the hold duration expires? When the hold duration expires for a mailbox item in the Recoverable Items folder, the item is permanently deleted (purged) from the inactive mailbox. If there's no duration specified for the hold placed on the inactive mailbox, items in the Recoverable Items folder are never purged (unless the hold duration for the inactive mailbox is changed).

  • Is an Exchange retention policy still processed on inactive mailboxes? If an Exchange retention policy (the messaging records management, or MRM, feature in Exchange Online) was applied to a mailbox when it was made inactive, the deletion policies (which are retention tags configured with a Delete retention action) will continue to be processed on the inactive mailbox. That means items that are tagged with a deletion policy are moved to the Recoverable Items folder when the retention period expires. Those items are then purged from the inactive mailbox when the hold duration for an item expires.

    Conversely, any archive policies (which are retention tags configured with a MoveToArchive retention action) that are included in the retention policy assigned to an inactive mailbox are ignored. That means items in an inactive mailbox that are tagged with an archive policy remain in the primary mailbox when the retention period expires. They're not moved to the archive mailbox or to the Recoverable Items folder in the archive mailbox. Because a user can't sign in to an inactive mailbox, there's no reason to consume datacenter resources to process archive policies.

  • To check the new hold duration for a Litigation Hold, run the following commands

      Get-Mailbox -InactiveMailboxOnly -Identity <identity of inactive mailbox> | FL LitigationHoldDuration
    
  • Like regular mailboxes, the Managed Folder Assistant (MFA) also processes inactive mailboxes. In Exchange Online, the MFA processes mailboxes approximately once every seven days. After you change the hold duration for an inactive mailbox, you can use the Start-ManagedFolderAssistant cmdlet to immediately start processing the new hold duration for the inactive mailbox. Run the following command.

    Start-ManagedFolderAssistant -InactiveMailbox <identity of inactive mailbox>
    
  • If many holds are placed on an inactive mailbox, not all of the hold GUIDs will be displayed. You can run the following command to display the GUIDs for all holds (except Litigation Holds) that are placed on an inactive mailbox.

    Get-Mailbox -InactiveMailboxOnly -Identity <identity of inactive mailbox> | Select-Object -ExpandProperty InPlaceHolds