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Mailbox Migration and Administering Exchange Online in Microsoft Office 365

Moving mailboxes back to on-premises Exchange

Moving mailboxes back to on-premises can be facilitated only through an Exchange hybrid environment. Otherwise, you will need to rely on third-party tools. Unlike having the cutover and staged migration options from the EAC and ECP, when moving mailboxes to Office 365, there are no built-in options to carry out the reverse.

As you saw in Chapter 11, after you have implemented an Exchange hybrid environment, the move of a mailbox to Office 365 is done by carrying out a remote move request. To move mailboxes back on-premises, you need to take into consideration whether the mailboxes you want to move were created in Office 365 from the very beginning or whether they were first created on-premises and then moved to Office 365.

Mailbox originally created on-premises

If the mailbox you want to migrate from Office 365 was initially created on-premises and then migrated to the cloud, all you have to do is submit a new remote move request from the Exchange Online organization to the Exchange on-premises organization through the Exchange Management Console (EMC). Follow these steps to see how this is accomplished:

  1. Start the EMC. Expand the Microsoft Exchange On-Premises node and navigate to the Recipient Configuration node. As shown in Figure 12-33, right-click the Recipient Configuration node, right-click a mailbox in the middle pane, and select New Remote Move Request from the drop-down menu.

    Figure 12-33

    Figure 12-33 Remote Move Request from Office 365.

  2. Follow the steps in the Remote Move Request Wizard, as in Chapter 11. When you get to the Move Settings page, select your on-premises domain in the Target Delivery Domain box. In the Remote Target Database box, if you are migrating to an Exchange 2010 server, use the format <Server>\<Database Name>, as shown in Figure 12-34. If you are migrating to an Exchange 2003 or 2007 server, use the format <Server>\<Storage Group>\<Database Name>; for example, MAIL\First Storage Group\Mailbox Database.

    Figure 12-34

    Figure 12-34 Move Settings page.

  3. Complete the rest of steps in the New Remote Move Request Wizard, and then click New to initiate the move request.

Mailbox originally created in Exchange Online

If the Exchange Online mailbox you want to move back to on-premises Exchange was originally created in Office 365, you will need to first set the ExchangeGUID property on the associated on-premises mailbox. You need to do this because the ExchangeGUID property is not synchronized back to the associated on-premises mailbox if the mailbox was initially created in Office 365. For a remote move request to succeed, the value stored in the ExchangeGUID property must be the same for the mailbox in Office 365 and the associated on-premises remote mailbox.

Follow these steps to check and set the ExchangeGUID property for the on-premises remote mailbox:

  1. Start the EMC on your on-premises Exchange hybrid server or management computer.

  2. Check if the ExchangeGUID property on the on-premises remote mailbox is set by entering the following command. Figure 12-35 shows an example of the output as a result of issuing the command:

    Get-RemoteMailbox <alias of cloud mailbox to migrate back on-premises> | For-
    mat-List ExchangeGUID
    Figure 12-35

    Figure 12-35 Checking the value of ExchangeGUID.

  3. If the return value for ExchangeGUID is not all zeros, as shown in Figure 12-35, then ExchangeGUID is set. You can immediately initiate a remote mailbox move back to on-premises Exchange by following the steps outlined in the Mailbox originally created on-premises section.

  4. If the return value for ExchangeGUID is all zeros, then ExchangeGUID is not set. On a separate computer, start the Windows Azure Active Directory Module for Windows PowerShell and connect to Exchange Online. Do not use the Exchange Management Shell. As a reminder, you can use the following syntax to connect to Exchange Online through remote Windows PowerShell:

    Import-Module MSonline
    
    $cred = Get-Credential
    
    Connect-MsolService -Credential $cred
    
    $Session = New-PSSession -ConfigurationName Microsoft.Exchange-ConnectionUri
    https://ps.outlook.com/powershell/ -Credential $cred -Authentication Basic
    -AllowRedirection
    
    Import-PSSession $Session -AllowClobber
  5. Enter the following command to retrieve ExchangeGUID for the Exchange Online mailbox, and write down the returned value:

    Get-Mailbox <alias of the cloud mailbox to migrate back to on-premises> \ For-
    mat-List ExchangeGUID
  6. Go back to the Exchange Management Shell window, and enter the following command to set the value of the ExchangeGUID property on the on-premises remote mailbox:

    Set-RemoteMailbox <alias of cloud mailbox to move> -ExchangeGUID <GUID>
  7. Start an unscheduled directory synchronization process using the Start-OnlineCoexistenceSync command. Refer to Chapter 4, if you need a refresher on how to do this.

  8. After directory synchronization is complete, you can follow the steps outlined in the preceding section to move the mailbox from the cloud back to on-premises.