Migrate All Mailboxes to the Cloud with a Cutover Exchange Migration

• What happens during a cutover Exchange Migration
  
• Before you begin
  
• Step 1   Start a migration batch
  
• Step 2   Configure the connection settings
  
  • Automatically detect connection settings with Autodiscover
    
  • Manually specify connection settings
    
• Step 3   Run the migration batch
  
• Step 4   Complete the migration
  
• Step 5   Implement a single sign-on solution (optional)
  
• Step 6   Remove your on-premises Exchange organization (optional)
  
• Best practices
  
• Next steps
  

When you migrate Exchange mailboxes to the cloud in a cutover Exchange migration:

• The migration service provisions new mailboxes in your cloud-based organization. It creates a cloud-based mailbox for each user account in your on-premises Exchange organization. On-premises distribution groups and contacts are also migrated to the cloud.
  
• After the new cloud-based mailboxes are created, the migration service migrates e-mail messages, contacts, and calendar items from the Exchange mailboxes to the corresponding cloud-based mailboxes.
  
• After the initial migration, the Exchange and cloud-based mailboxes are synchronized every 24 hours, so that new e-mail sent to the Exchange mailbox is copied to the corresponding cloud-based mailbox.
  

When you're ready, you can route e-mail directly to the cloud-based mailboxes, complete the migration, and then remove your on-premises Exchange organization.

Important:
If you’ve activated and installed the Microsoft Online Services Directory Synchronization tool, you can’t run a cutover Exchange Migration. If you’ve installed the directory synchronization tool, you can deactivate directory synchronization and then run a cutover Exchange migration. For more information, see Manage directory synchronization.

• Configure Outlook Anywhere on your on-premises Exchange server   The e-mail migration service uses RPC over HTTP, or Outlook Anywhere, to connect to your on-premises Exchange server. For information about how to set up Outlook Anywhere for Exchange 2010, Exchange 2007, and Exchange 2003, see the following:
  
  • Exchange 2010: Enable Outlook Anywhere
    
  • Exchange 2007: How to Enable Outlook Anywhere
    
  • Exchange 2003: Deployment Scenarios for RPC over HTTP
    
  • How to Configure Outlook Anywhere with Exchange 2003
    
  Important   Your Outlook Anywhere configuration must be configured with a certificated trusted by a certificate authority (CA). It can't be configured with a self-signed certificate. For more information, see How to Configure SSL for Outlook Anywhere.
  
• Verify that you can connect to your Exchange organization using Outlook Anywhere   Try one of these connection methods:
  
  • Use Microsoft Office Outlook from outside your corporate network to connect to Exchange.
    
  • Use the Microsoft Exchange Remote Connectivity Analyzer (ExRCA) to test your connection settings.
    
  • Run the following Windows PowerShell commands.
    
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    $PSCredentials = Get-Credential
    

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    Test-MigrationServerAvailability -Autodiscover -EmailAddress <migration administrator e-mail address> -Credentials $PSCredentials
    

• Assign the migration administrator permissions to access mailboxes in your Exchange organization   The on-premises account that you use to run a migration batch must have the necessary permissions to access all user mailboxes. You can assign the Full Access permission for individual mailboxes or assign the Receive As permission for a mailbox database. For more information, see the following:
  

  Exchange 2010	Allow Mailbox Access
  Exchange 2007	Use the Add-MailboxPermission cmdlet to add permissions to a mailbox How to allow mailbox access
  Exchange 2003	Microsoft Knowledge Base article 268754 - How to assign users or groups full access to other user mailboxes Microsoft Knowledge Base article 821897 - How to assign service account access to all mailboxes in Exchange Server 2003

• Add your Exchange organization as an accepted domain of your cloud-based e-mail organization   The migration service uses the SMTP address of your on-premises mailboxes to create the Windows Live ID (and e-mail address) for the new cloud-based mailboxes. Migration will fail if your Exchange domain isn't an accepted domain (or the primary domain) of your cloud-based organization. For more information, see Create Accepted Domains - Office 365 for enterprises.
  
• Disable unified messaging   If the mailboxes you are migrating are enabled for unified messaging (UM), you have to disable UM on the mailboxes before you migrate them. You can then enable UM on the mailboxes after the migration is complete. For more information, see Plan to Migrate UM-Enabled Mailboxes.
  

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1. Select Manage My Organization > Users & Groups > E-Mail Migration > New. On the Welcome to E-mail Migration page, select one of the following migration types:
   
   • Exchange 2007 and later versions - Automatically detect connection settings with Autodiscover   Select this option if you want the migration service to automatically connect to your on-premises Exchange server using the Autodiscover service.
     
   • Exchange 2003 and later versions - Manually specify connection settings   Select this option if your on-premises messaging system is running Exchange 2003 or if you are running a later version but want to manually provide the connection settings to your on-premises mail server.
     
2. Click Next after you select a migration type.
   

Provide the credentials and connection settings for your on-premises Exchange server depending on the migration type that you selected. Perform only one of the following tasks based on your migration type.

1. Decide if you want Microsoft Exchange to send a status e-mail message to other users when the migration batch is done running. If so, click the Browse to select one or more users.
   
2. Review the number of mailboxes, distribution groups, and contacts that will be migrated.
   
   • To start processing the migration batch, click Run.
     
   • To cancel the current migration batch and return to step 1, click Start Over.
     

After you've run all your Exchange migration batches for your on-premises Exchange organization, you're ready to complete the migration. Follow these steps:

1. Configure your MX record to point to your cloud-based e-mail organization   Until you change your MX record, e-mail sent to users is still routed to their on-premises Exchange mailboxes. When a user mailbox is successfully migrated, the on-premises Exchange mailbox and cloud-based mailbox are synchronized once every 24 hours until you complete the overall migration. When you configure your organization's MX record to point to your cloud-based e-mail organization, all e-mail is sent directly to the cloud-based mailboxes.
   After you change the MX record and verify that all e-mail is being routed to the cloud-based mailboxes, you're ready to complete the migration.
   Important   It can take from 24 to 72 hours for the updated MX record to be propagated. Wait at least 24 hours after you change the MX record before you complete the migration. Verify that mail is being routed to cloud-based mailboxes before you complete the migration.
   
2. Complete the overall migration process   Click Complete Migration in the E-Mail Migration pane. What happens when you click Complete Migration?
   
   • Microsoft Exchange runs a final synchronization for all mailboxes. After this, e-mail is no longer synchronized between the on-premises Exchange mailboxes and cloud-based mailboxes.
     
   • Microsoft Exchange sends a final status e-mail message after the migration is complete.
     
   When you complete a migration, you have two options for how the migration service handles errors that occur during the final synchronization:
   
   • Ignore synchronization errors   The migration service ignores any final synchronization errors and completes the migration. If there are errors, the status message sent to the administrator contains a link to the MigrationErrors.csv file.
     
   • Don't ignore synchronization errors   If there are any final synchronization errors, the migration service doesn't complete the migration. Instead, it displays a link to the Error Report for Synchronization Failures. If you don't ignore synchronization errors, the migration will be completed only when there are no synchronization errors.
     

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After all mailboxes are migrated to the cloud, you can implement a single sign-on solution to enable users to use their on-premises Active Directory credentials (username and password) to access their Office 365 mailboxes and existing on-premises resources. You implement a single sign-on solution by deploying Active Directory Federation Services 2.0 (AD FS 2.0). For more information, see Cutover Exchange Migration and Single Sign-on.

After you’ve verified that all e-mail is being routed directly to the cloud-based mailboxes, completed the migration, and no longer need to maintain your on-premises e-mail organization or don’t plan on implementing a single sign-on solution, you can uninstall Exchange from your servers and remove your on-premises Exchange organization. For more information, see the following:

• Modify or Remove Exchange 2010
  
• How to Remove an Exchange 2007 Organization
  
• How to Uninstall Exchange Server 2003
  

Here are some tips to optimize your Exchange migration:

• Change the DNS Time-to-Live (TTL) setting on your MX record   Before you start to migrate mailboxes, change the DNS TTL setting on your current MX record to a shorter interval, such as 3600 seconds (one hour). Then, when you change your MX record to point to your cloud-based e-mail organization after all mailboxes are migrated, the updated MX record should propagate more quickly because of the shortened TTL interval.
  
• Communicate with your users   Give users a heads-up that you are migrating the content of their on-premises Exchange mailboxes to your cloud-based organization. Consider the following:
  
  • Ask users to delete old or unnecessary e-mail messages from their Exchange mailbox before migration. This helps reduce the amount of data that has to be migrated and can help reduce the overall migration time. Or you can clean up their mailboxes yourself.
    
  • Suggest that users to back up their Inbox.
    
  • Tell users when they can use their cloud-based account to access the e-mail that was migrated from their on-premises account. Don't give users access to their cloud-based accounts until you're ready to complete the migration.
    Need a good way to provide users with their sign-in credentials and autogenerated password for their new cloud-based accounts? See Send a Welcome Message to New Users.
    

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If you have a Microsoft Office 365 e-mail organization, you must assign licenses to new mailboxes or they will be disabled when the grace period ends. For more information, see Assign a License to New Mailboxes in Office 365.