Understand Remote Mailbox Move and UM
Applies to: Office 365 for enterprises
If you need to migrate an Exchange mailbox from one Active Directory forest to another, you need to perform a remote mailbox move, also known as a cross-forest mailbox move. If the mailboxes you’re moving are enabled for Exchange Unified Messaging, you have some extra considerations for the migration. This article assumes that you’re familiar with Unified Messaging and have a general understanding of how a remote mailbox move works. For more information, see Understanding Move Requests.
Before you begin
To learn how to install and configure Windows PowerShell and connect to the service, see Use Windows PowerShell in Exchange Online.
If the mailbox will have a different UM status in the target forest than it does in the source forest, you can make the move less complex by doing the following:
- If the mailbox is enabled for UM in the source forest, but you don't want it to be enabled in the target forest, disable UM on the mailbox prior to the move.
- If the mailbox isn't enabled for UM in the source forest, but you want it enabled in the target forest, enable the mailbox for UM in the target forest after the move.
Migrate mailboxes that are enabled for UM
You perform a remote mailbox move using the MoveRequest cmdlets. These have been extended in Exchange 2010 SP1 to address issues users encountered when migrating mailboxes enabled for UM using earlier versions of Exchange.
- You no longer need to disable and then re-enable UM on the mailbox before and after the move.
- The amount of time voice mail is unavailable during the migration has been reduced.
To take advantage of both of these improvements, you need to:
Map the UM mailbox policies in the source forest to the UM mailbox policies in the target forest. To do this, you add the name of the UMMailboxPolicy object in the source forest to the SourceForestPolicyNames attribute on the UMMailboxPolicy object in the target forest. Note that the SourceForestPolicyNames attribute accepts multiple values, must be unique, and is populated by default with the same name as the UM mailbox policy. For more information about this attribute, see More information about the SourceForestPolicyNames attribute. For more information about how to map UM mailbox policies, see Map Existing UM Mailbox Policies to the Cloud.
Run the New-MoveRequest cmdlet. For more information, see New-MoveRequest with the SuspendWhenReadyToComplete parameter set to
$true. This option pauses the New-MoveRequest cmdlet immediately before it completes.
Note If you don’t use the SuspendWhenReadyToComplete parameter during the migration, a voice mail outage will occur when the migration process completes. This happens because your telephony system is still sending calls to the UM servers in the source forest. You have to update your telephony configuration for the migrated phone numbers to point to the UM servers in the target forest.
Update your PBX configuration to point to the UM servers in the target forest and resume the move request by running the Resume-MoveRequest cmdlet. For more information, see Resume-MoveRequest. For information about how to point your PBX to UM in the cloud, see Forward Calls from Your Physical Telephone Device to UM.
Troubleshoot the migration
Migration completes with warning Under rare circumstances, when the New-MoveRequest cmdlet is run, the initial UM validation succeeds but, as the mailbox move completes, the mailbox fails to be enabled for UM in the target forest. When this occurs, the mailbox move completes with a warning. The warning message, which can be obtained using the Get-MoveRequestStatistics cmdlet, looks like this:
Warning: User 'John Doe' can't be enabled for Unified Messaging in the target forest for the following reason: Extension 12345 is already assigned to another user on dial plan DP1 or an equivalent dial plan. Please fix the problem and enable the user for Unified Messaging manually.
Solution Manually enable the mailbox for UM in the target forest.
UM mailbox has secondary extensions In the source forest, you can assign extensions from multiple UM dial plans to a mailbox that’s enabled for UM. However, only extensions from the primary UM dial plan are used to enable UM on the mailbox in the target forest. Assigned extensions from secondary UM dial plans aren’t copied over.
Solution Manually copy over extensions from secondary UM dial plans.
The mailbox migration process
While a mailbox move is in progress, UM continues to operate for the mailboxes in the source forest because the mailboxes are still UM enabled.
Note If the mailbox is enabled for UM, the migration performs a series of UM-specific validations, including looking for a matching UMMailboxPolicy object in the target forest and validating that the UM extensions assigned to the mailbox are unique in the target forest. If the validation fails, New-MoveRequest returns an error immediately.
During the migration process, the migration process does the following in the target forest:
- Detects that the mailbox being moved is enabled for UM, and gets the name of the UM mailbox policy for the mailbox in the source forest.
- Looks for this source UM mailbox policy name in the SourceForestPolicyNames attributes of the UM mailbox policies in the target forest.
- Determines which UM extensions are currently assigned to the mailbox in the source forest.
- Using the extensions and the UM mailbox policy for the mailbox in the source forest found earlier, enables the mailbox for UM in the target forest with the same extensions and the target UM mailbox policy that was mapped to the source policy.
- Copies information about the user's UM PIN to the target forest, preserving the user's existing UM PIN during migration.
- Sends a UM welcome message to the user, showing the access telephone number for the UM dial plan in the target forest. The telephone access number is the number users dial on their phone to access Outlook Voice Access.
In the source forest, UM does the following:
- Updates the Active Directory mailbox object to a mail-enabled user object.
- Removes all UM configuration on the mail-enabled user object.
As the mailbox move completes, the mailbox in the source forest is deleted and the mailbox in the target forest becomes functional. If you update your telephony configuration as the mailbox move completes, you can reduce the period during which voice mail isn’t working. Using the SuspendWhenReadytoComplete parameter can help in coordinating the migration between Exchange and telephony administrators.
More information about the SourceForestPolicyNames attribute
When you’re specifying the SourceForestPolicyNames attribute on the UMMailboxPolicy object, remember that this attribute can hold multiple values, must be unique in the target forest and, by default, is the same as the UMMailboxPolicy object name.
- Multiple values You can have multiple UMMailboxPolicy objects in the source forest mapped to a single UMMailboxPolicy object in the target forest.
- Must be unique You can’t specify the same value for the SourceForestPolicyNames attribute in two different UMMailboxPolicy objects in the same forest. This restriction ensures that the migration process finds only one match in the target forest for any given UM mailbox policy.
- **Default value matches the UM mailbox policy name **When you create a new UM mailbox policy, the SourceForestPolicyNames attribute is automatically populated with the same name. So if you create UM mailbox policies in the target forest with the same name as the UM mailbox policies in the source forest, you can eliminate the need to manually configure the SourceForestPolicyNames attribute.