Managing Compliance in Microsoft Exchange Server 2010

Putting a mailbox on litigation hold

When you place a mailbox on litigation hold (sometimes referred to as “legal hold”), Exchange stops removing items when their deleted items retention period expires, and any attempts by the user to delete or change items are retained in the dumpster. Items remain in the dumpster indefinitely until the litigation hold is released and are not subject to any quotas. Because items are retained, they remain available to be indexed and can be retrieved by discovery searches (see the section “Discovery searches” later in this chapter).

Exchange 2010 RTM only supports placing a mailbox on litigation hold using the Set-Mailbox cmdlet. For example:

Set-Mailbox -Identity 'Ruth, Andy (VP Sales)' -LitigationHoldEnabled $True
-RetentionComment 'Mailbox placed on litigation hold on 16 May 2010'
-RetentionURL 'http://intranet.contoso.com/LegalHold.html'
-LitigationHoldDate '4/1/2011 09:00'
-LitigationHoldOwner 'Legal Department'

With Exchange 2010 SP1, you can set litigation hold on a mailbox with EMC in much the same way as you set retention hold on a mailbox (Figure 15-20).

Figure 15-20 Setting litigation hold on a mailbox with EMC.

The RetentionComment and RetentionURL properties are used to populate the Account Settings section of Outlook 2010’s backstage area to inform users that their mailbox has been placed on hold. The –LitigationHoldDate and –LitigationHoldOwner parameters are only available with Exchange 2010 SP1 and are used to hold the date and time when the hold was enforced and the account that enforced the hold. Exchange completes these details automatically when you place a mailbox on litigation hold using EMC or ECP, so if you put a mailbox on hold with EMS you should also provide these details.

Releasing the mailbox from litigation hold is done by reversing the process:

Set-Mailbox -Identity 'Akers, Kim' -LitigationHoldEnabled $False
-RetentionComment $Null

To set litigation hold through ECP, select the mailbox and scroll down to the Mailbox Features section to reveal the option (Figure 15-21). You can then enable the hold and input an appropriate retention comment and URL for users to access more information about what this new status means for them. After you save the new setting, Exchange updates the mailbox properties (as previously) and advises you that it might take up to 60 minutes before the hold becomes effective.

Figure 15-21 Putting a mailbox on litigation hold with ECP.

The exact delay depends on your Active Directory infrastructure and how quickly updated mailbox settings are replicated. Two influences are in play. First, Active Directory must replicate the updated litigation hold property to all global catalog servers before you can be assured that the setting applies across the forest. Second, the Store caches Active Directory data about mailbox properties for performance reasons and therefore will not know that the litigation hold setting has changed for the mailbox until the next time that the Store refreshes its cache. The updated litigation hold setting will be fetched from Active Directory and become effective the next time that the Store refreshes its cache. The complete cycle of Active Directory replication and Store cache refreshes could take up to an hour. For this reason, it is a good idea to implement litigation holds, if possible, at a time when users are not actively using their mailboxes.