Migrate a Subset of Mailboxes to the Cloud with a Staged Exchange Migration

• What happens during a staged Exchange migration
  
• Before you begin
  
• Step 1   Start a staged Exchange migration batch
  
• Step 2   Configure the connection settings
  
  • Automatically detect connection settings with Autodiscover
    
  • Manually specify connection settings
    
• Step 3   Upload the CSV file
  
• Step 4   Run the migration
  
• Step 5   Convert on-premises mailboxes to mail-enabled users
  
• Step 6   Run additional migration batches
  
• Step 7   Complete the migration
  
• Step 8   Remove your on-premises Exchange organization (optional)
  
• Best practices
  
• Next steps
  

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When you use a staged Exchange migration and CSV file to migrate on-premises Exchange mailboxes to the cloud, the migration service does the following:

• It verifies that OLSync or the Microsoft Online Services Directory Synchronization tool is enabled for your cloud-based organization.
  
• It checks that a mail-enabled user (MEU) exists in the cloud-based e-mail organization for each entry in the CSV file.
  
• It converts the MEU to a mailbox.
  
• It configures mail forwarding by populating the TargetAddress property on the on-premises mailbox with the e-mail address of the cloud-based mailbox. This enables e-mail sent to an on-premises mailbox to be forwarded to the corresponding cloud-based mailbox.
  
• It e-mails a report that lists the cloud-based mailboxes that were successfully created and for which e-mail forwarding was configured. At this point, you can tell users to start using their new cloud-based mailbox. This report also lists any migration errors.
  
• It 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 aren't synchronized. New e-mail sent to the Exchange mailbox is forwarded to the corresponding cloud-based mailbox.
  
• It e-mails a final report when the data migration is complete.
  

Be sure to plan your e-mail migration carefully, especially verifying your ability to connect to your Exchange server. When you plan, check out Best practices.

• Install and configure a directory synchronization tool for your cloud-based organization   OLSync or the Microsoft Online Services Directory Synchronization tool must be running to perform a staged e-mail migration. The directory synchronization tool creates the MEUs that are converted to mailboxes during the migration. If OLSync or the Microsoft Online Services Directory Synchronization tool isn't installed, you can only perform a cutover Exchange migration that migrates all your on-premises mailboxes to the cloud. For more information about the different types of migration, see E-Mail Migration Overview.
  For more information about how to install a directory synchronization tool, see the following:
  
  • Microsoft Live@edu   Implement Outlook Live Directory Sync for Live@edu
    
  • Office 365 for enterprises   Active Directory synchronization: Roadmap
    
• Plan for user identity management   After your on-premises mailboxes are migrated to the cloud, the synchronization process continues to update the user attributes on the mailbox according to changes made in the on-premises Active Directory. This means that the “source of authority” for managing user objects is your on-premises directory, and that you can’t manage user mailbox properties in Exchange Online. But after you perform a staged Exchange migration you can configure the Microsoft Online Services Directory Synchronization tool so that the source of authority is the Office 365 directory. This lets you manage mailbox properties in Exchange Online. For more information about user identity management after migrating mailboxes to Office 365, see the following:
  
  • Plan for User Identity in a Staged Exchange Migration
    
  • Directory synchronization and source of authority
    
  • Manage directory synchronization
    
• Configure Outlook Anywhere on your on-premises Exchange server   The 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 2007 and Exchange 2003, see the following:
  
  • 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.
    
• Prepare the CSV file   Identify the group of users whose on-premises mailboxes you want to migrate to the cloud. Include these users in the CSV file that will make up the migration batch.
  Important   The CSV file for a staged Exchange migration batch can contain a maximum of 1,000 rows. To migrate more than a 1,000 mailboxes, you have to submit additional CSV files.
  Here are the attributes to use for the mailboxes you want to migrate:
  
  • EmailAddress specifies the SMTP e-mail address for the on-premises mailbox. This attribute is required.
    
  • Password is the password that will be set on the new cloud-based mailbox. This attribute is optional.
    
  • ForceChangePassword specifies whether a user must change the password the first time they sign in to their new cloud-based mailbox. Use either True or False for the value of this parameter. This attribute is optional.
    Important   If you’ve implemented a single sign-on solution by deploying Active Directory Federation Services 2.0 in your on-premises organization, you must use False for the value of the ForceChangePassword attribute.
    
  Here's an example of the format for the CSV file. In this example, three on-premises mailboxes are migrated to the cloud.
  
  Copy

  EmailAddress,Password,ForceChangePassword
  pilarp@tailspintoys.com,P@ssw0rd,False
  tobyn@tailspintoys.com,P@ssw0rd,False
  iant@tailspintoys.com,P@ssw0rd,False
  

  For more information, see Prepare a CSV File for a Staged Exchange Migration.
  
• Assign the migration administrator permissions to access mailboxes in your Exchange organization   The on-premises account that you use to run the migration 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 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 e-mail address for the new cloud-based mailboxes. If you are a Live@edu organization, 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 the following topics:
  
  • Create Accepted Domains - Office 365 for enterprises
    
  • Create Accepted Domains - Live@edu
    
• 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. Click Browse to select the CSV file for the migration batch.
   
2. After you select the CSV file, click Next.
   Important   When you click Next, you are agreeing to give the migration service permission to make changes to the properties of the on-premises mailboxes to enable e-mail forwarding. For more information, see Give the Migration Service Permission to Configure Mail Forwarding for Cloud-based Mailboxes.
   
3. Microsoft Exchange checks the CSV file for the following:
   
   • It isn't empty.
     
   • It uses comma-separated formatting.
     
   • It doesn't contain more than 1,000 rows.
     
   • It includes only the allowed attributes in the header row, and verifies that the required EmailAddress attribute is included.
     
   • It contains rows with the same number of columns as the header row.
     
   If any one of these checks fails, you'll get an error that describes the reason for the failure. At this point, you have to fix the CSV file and resubmit it. For more information, see Prepare a CSV File for a Staged Exchange Migration.
   If the CSV file successfully passes these checks, you'll move on to the Start the migration page.
   

In addition to the checks described in step 3, Microsoft Exchange also checks for data validation errors in the CSV file at this point in the process. If data validation errors are found, a warning and a link to the validation error report are displayed on the Start the migration page. The migration process isn't terminated if data validation errors are found, but on-premises mailboxes won't be migrated to the cloud for the rows that have errors.

For example, a data validation error is displayed if the on-premises mailbox can't be found using the SMTP address in the CSV file or if an MEU for an on-premises mailbox can't be found in the cloud-based e-mail organization. For more information, see Troubleshoot Migration Validation Errors.

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 Browse to select one or more users.
   
2. Review the number of mailboxes 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 a migration batch is finished running and you’ve verified that all mailboxes in the batch are successfully migrated and the initial synchronization of mailbox items to the cloud is complete, we recommend that you convert the on-premises mailboxes in the migration batch to mail-enabled users. Why? After a staged Exchange migration, a user has an on-premises mailbox and a cloud mailbox. Because mail sent to the user’s on-premises mailbox is forwarded to their cloud mailbox after migration, users need to connect to their cloud mailboxes to access their e-mail. But if a person uses Microsoft Outlook to open their mailbox, the Autodiscover service still tries to connect to the on-premises mailbox. After you convert on-premises mailboxes to mail-enabled users, the Autodiscover service uses the mail-enabled user to connect Outlook to the cloud mailbox after the user creates a new Outlook profile.

Another important reason to convert on-premises mailboxes to mail-enabled users is to retain proxy addresses from the cloud-based mailboxes by copying proxy addresses to the mail-enabled user. This lets you manage cloud-based users from your on-premises organization by using Active Directory. Also, if you decide to decommission your on-premises Exchange organization after all mailboxes are migrated to the cloud, the proxy addresses you’ve copied to the mail-enabled user will remain in your on-premises Active Directory.

For more information and to download scripts that you can run to convert mailboxes to mail-enabled users, see the following:

• Convert Exchange 2007 mailboxes to mail-enabled users
  
• Convert Exchange 2003 mailboxes to mail-enabled users
  

If there are errors in a migration batch or you want to migrate additional on-premises mailboxes to the cloud, you can start a new migration batch and submit a new CSV file that contains the information about the mailboxes you want to migrate.

You don't have to enter connections when you start a new migration batch because they persist from the previous batch. When you start a new migration batch, the migration service connects to your on-premises Exchange server and verifies that OLSync or the Microsoft Online Services Directory Synchronization tool is still installed and running. When this query is complete, the migration service prompts you to select the CSV file.

After you've migrated all your on-premises mailboxes to your cloud-based organization, you're ready to complete the migration. Follow these steps:

1. Configure your MX record to point to you cloud-based e-mail organization   Until you change your MX record, e-mail sent to users is still routed to their Exchange mailboxes and then forwarded to the corresponding cloud-based mailboxes. 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 sent directly to 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?
   
   • The migration service cleans up any records related to the previous migration batches.
     
   • The migration service checks to see if there are any MEUs in your cloud-based organization that correspond to on-premises mailboxes that haven't been migrated to the cloud. If it finds MEUs that haven't been converted to mailboxes, it displays a warning message.
     
   • Microsoft Exchange sends a final status e-mail message after the migration is complete.
     

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After you’ve migrated all on-premises mailboxes to the cloud, converted all on-premises mailboxes to mail-enabled users, and have verified that all e-mail is being routed directly to the cloud mailboxes, you may no longer need to maintain all your on-premises Exchange servers for mail delivery. If this is the case, you can uninstall Exchange from your servers in your on-premises organization. However, we strongly recommended that you maintain at least one Exchange server so that you have access to Exchange System Manager (Exchange 2003) or Exchange Management Console/Exchange Management Shell (Exchange 2007) to manage mail-related attributes on the on-premises mail-enabled users. For Exchange 2007, the Exchange server that you maintain should have the Hub Transport, Client Access, and Mailbox server roles installed. For more information, see the following:

• How to Remove an Exchange 2007 Organization
  
• How to Uninstall Exchange Server 2003
  

Caution:
Removing your Exchange organization can have unintended consequences. Before uninstalling Exchange from servers in your on-premises organization or removing your entire on-premises Exchange organization, we recommend that you contact Microsoft Support.

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 their on-premises mailbox to the cloud. 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 back up their Inbox.
    
• When you receive the Mailboxes Ready Report for a migration batch, tell users to start using their cloud-based mailboxes to send and receive e-mail   Give them the password to their new cloud-based mailbox and send them links to the following topics to help them connect to their cloud-based mailbox:
  
  • Connect Outlook to This Account
    
  • How to Sign In to Outlook Web App
    
• Require users to change their password   In the CSV file, set the ForceChangePassword attribute to True. This forces users to change the password the first time they sign in to their new cloud-based mailbox and helps ensure that only the user knows the password. Be sure to encourage people to use strong passwords.
  Tip   If you use a unique password for each row in the CSV file, you can use the mail merge process in Microsoft Office Word and an edited version of your CSV file to provide users with the password for their new cloud-based accounts. See Send a Welcome Message to New Users.
  

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• Assign licenses to Office 365 users   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.
  
• Create an Autodiscover DNS record   After all on-premises mailboxes are migrated to the cloud, you can configure an Autodiscover DNS record for your cloud-based organization to enable users to connect to their new cloud-based mailbox with Microsoft Outlook and mobile clients. This new Autodiscover DNS record has to use the same namespace that you’re using for your cloud-based organization. For example, if your cloud-based namespace is cloud.contoso.com, the Autodiscover DNS record you need to create is autodiscover.cloud.contoso.com.
  Exchange Online uses a CNAME record to implement the Autodiscover service for Outlook and mobile clients. The Autodiscover CNAME record must contain the following information:
  
  • Alias   autodiscover
    
  • Target   autodiscover.outlook.com
    
  For more information, see Use a CNAME Record to Enable Outlook to Connect.