Email Migration Overview

 

Applies to: Office 365 for professionals and small businesses, Office 365 for enterprises, Live@edu

Topic last modified: 2012-05-02

You can use Email Migration in the Exchange Control Panel to migrate mail from an on-premises messaging system to your cloud-based organisation. You can migrate mailboxes and mailbox data from Microsoft Exchange Server 2010, Exchange Server 2007, and Exchange Server 2003, or migrate mailbox data from an IMAP messaging system. Exchange Online provides the following types of migration:

Microsoft Live@edu: If your institution is using Hotmail as part of the Live@edu experience, you may be able to migrate your email organisation to Outlook Live. For more information, see Hotmail to Outlook Live Migration for Live@edu.

Cutover Exchange migration

Use Email Migration to provision new cloud-based mailboxes and then migrate mailbox data to the cloud from your on-premises Exchange server. This type of migration is called a cutover because all on-premises mailboxes are migrated in preparation for moving your entire email organisation to the cloud. The contacts and distribution groups in your on-premises organisation are also migrated. You can migrate a maximum of 1,000 mailboxes from your on-premises Exchange organisation to the cloud.

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 Microsoft Online Services Licence to New Mailboxes.

How the cutover Exchange migration process works

Here's an overview of the cutover Exchange migration process. For step-by-step instructions, see Migrate All Mailboxes to the Cloud with a Cutover Exchange Migration.

Important   Before you run an Exchange migration, your on-premises Exchange organisation must be an accepted domain of your cloud-based email organisation.

  1. Start a new migration using Email Migration and select one of the following Exchange migration types:

    • Exchange 2007 and later versions - Automatically detect connection settings with Autodiscover.

    • Exchange 2003 and later versions - Manually specify connection settings

  2. After the migration service verifies the connection settings to your on-premises Exchange server and you run the migration, Microsoft Exchange does the following:

    • It uses the address book from your on-premises Exchange server to identify the mailboxes, distribution groups and contacts you want to provision in your cloud-based email organisation.

    • It provisions the new cloud-based mailboxes. Microsoft Exchange processes up to N migrations at one time, where N is the maximum number of mailboxes to migrate simultaneously that the administrator specified for the migration.

    • It creates distribution groups and contacts. The group membership from on-premises groups is recreated for the corresponding cloud-based group. If an on-premises mailbox fails to be migrated, that user can't be added to a cloud-based distribution group. When that mailbox is successfully migrated in a subsequent migration, the user will be added to the group.

    • It migrates mailbox data, which includes email messages, contacts and calendar items, to the new cloud-based mailboxes. This is called initial synchronisation.

  3. After the initial synchronisation process and mailboxes are successfully provisioned and migrated, the mailboxes in the on-premises Exchange organisation and the corresponding cloud-based mailboxes are synchronised every 24 hours. This is called incremental synchronisation. This means that any new messages sent to the mailboxes on the Exchange server are copied to the corresponding cloud-based mailboxes. Incremental synchronisation continues until the administrator completes the overall migration.

    Note   During incremental synchronisation, deletions made in an on-premises mailbox are synchronised to the corresponding cloud-based mailbox. This means that if a user deletes an item from the on-premises mailbox that was previously migrated to the cloud, it will be deleted from the cloud-based mailbox.

  4. When the migration has finished running, Microsoft Exchange sends a status email message to the administrator. A migration is done when all migration requests are either completed or failed. The status email message includes links to the following CSV files:

    • MigrationErrors.csv, which contains information about each mailbox that failed migration.

    • MigrationStatistics.csv, which contains information about the number of items migrated from each on-premises mailbox. This file also contains an auto-generated, 8-character alpha-numeric password for each mailbox that was migrated. Users are required to reset this password when they log on for the first time.

  5. Additional migration batches are started, if necessary. The migration service will skip any on-premises mailboxes, contacts or distribution groups that have already been migrated.

  6. After all mailboxes have been successfully migrated, the administrator updates the organisation's MX record to point to their cloud-based email organisation so that email messages are delivered directly to users' cloud-based mailboxes.

  7. After the change to the MX record has been propagated, the administrator completes the migration process. Microsoft Exchange does the following to complete the migration:

    • It runs a final synchronisation for all mailboxes. After this, email sent to the on-premises mailboxes is no longer copied to cloud-based mailboxes.

    • It sends a final status email message after the migration is complete.

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Staged Exchange migration

As an alternative to a cutover Exchange migration, you can use Email Migration and a CSV file to migrate a subset of your on-premises mailboxes to the cloud. This process is called a staged Exchange migration. This type of migration allows you to maintain short- or long-term coexistence between your on-premises and cloud-based email organisations. In this scenario, you can migrate some mailboxes to the cloud while maintaining the rest of the mailboxes in your on-premises mail environment.

Note   You can’t use a staged Exchange migration to migrate Exchange 2010 mailboxes. Additionally, this migration type is not available in Microsoft Office 365 for professionals and small businesses.

Using a staged Exchange migration, you can migrate user mailboxes and resource mailboxes only. Other recipient types, such as distribution groups, contacts and mail-enabled users are migrated to Office 365 through the process of directory synchronisation.

Important   To use a staged Exchange migration, you have to replicate user objects from your on-premises Active Directory service to your cloud-based email organisation. Depending on your organisation type, you have to install and configure a directory synchronisation tool before you can run a staged Exchange migration:

  • Microsoft Live@edu   Use Outlook Live Directory Sync (OLSync). For more information, see Implement Outlook Live Directory Sync for Live@edu.

  • Microsoft Office 365 for enterprises   Use the Microsoft Online Services Directory Synchronisation tool (DirSync). For more information, see Active Directory synchronisation: Roadmap.

    Important   After your on-premises mailboxes are migrated to the cloud, the synchronisation 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 Synchronisation tool so that the source of authority is the Office 365 directory. This allows you to manage mailbox properties in Exchange Online. For more information, see:

How the staged Exchange migration process works

Here's an overview of the staged Exchange migration process. For step-by-step instructions, see Migrate a Subset of Mailboxes to the Cloud with a Staged Exchange Migration.

  1. Install and configure OLSync or DirSync for your cloud-based organisation.

  2. Create a CSV file that contains a row for each on-premises mailbox that you want to migrate to the cloud. For more information, see Prepare a CSV File for a Staged Exchange Migration.

  3. Start a new migration using Email Migration and select one of the following Exchange migration types:

    • Exchange 2007 and later versions - Automatically detect connection settings with Autodiscover

    • Exchange 2003 and later versions - Manually specify connection settings

  4. After you provide the connection settings to your on-premises Exchange organisation, the migration service does the following:

    • Tests the connection settings to your on-premises Exchange server

    • Verifies that OLSync or DirSync is enabled, depending on your organisation type

    • Prompts you to submit a staged migration CSV file

    • Checks that a mail-enabled user (MEU) exists in the cloud-based email organisation for each entry in the CSV file

    • Converts the MEU to a mailbox

    • Configures mail forwarding by populating the TargetAddress property on the on-premises mailbox with the email address of the cloud-based mailbox

  5. After it creates and configures the cloud-based mailboxes, the migration service emails a report that lists the cloud-based mailboxes that were successfully created. At this point, you can tell users to start using their new cloud-based mailbox.

  6. The migration service then migrates email messages, contacts and calendar items from the Exchange mailboxes to the corresponding cloud-based mailboxes.

  7. Emails a final report when the data migration is complete.

  8. Additional migration batches and their corresponding CSV migration file are created and started, if necessary.

  9. After all on-premises mailboxes have been successfully migrated to the cloud, you can update your organisation's MX record to point to your cloud-based email organisation so that email messages are delivered directly to users' cloud-based mailboxes.

  10. After the change to the MX record has been propagated, you complete the migration process. The migration service does the following to complete the migration:

    • Cleans up any records relating to the previous migration

    • Checks to see if there are any MEUs in your cloud-based organisation that correspond to on-premises mailboxes that haven't been migrated to the cloud and displays a warning message

    • Sends a final status email message after the migration is complete

IMAP email migration

You can use Email Migration and a CSV file to migrate the contents of users' mailboxes from an IMAP messaging system to their cloud-based mailbox. This provides organisations with an effective way to move from an IMAP messaging system to a cloud-based email organisation. Supported IMAP servers include the following:

  • Courier-IMAP

  • Cyrus

  • Dovecot

  • UW-IMAP

  • Exchange 2000 Server or previous versions

  • Exchange 2003

  • Exchange 2007

  • Exchange 2010

How the IMAP migration process works

Here's an overview of the IMAP migration process. For step-by-step instructions, see Migrate E-Mail from an IMAP Server to Cloud-based Mailboxes.

  1. Create mailboxes in your cloud-based organisation for users. For more information, see:

  2. Create a CSV file that contains a row for each user whose IMAP mailbox you want to migrate. For more information, see Prepare a CSV file to Migrate Email from an IMAP Server.

  3. Start a new migration using Email Migration and select the IMAP migration type.

  4. Configure the migration:

    • Configure the connection settings to the IMAP server.

    • Select folders in the IMAP messaging system to exclude from the migration, such as Deleted Items and Junk Mail or shared and public folders.

    • Submit the CSV file.

  5. When you start the migration, Microsoft Exchange does the following:

    • It creates a migration request for each row in the CSV file. Each migration request contains the user name and encrypted password for the account in the IMAP messaging system.

    • It starts processing migration requests. This part of the process is called active mailbox migration or the initial synchronisation. For each user listed in the CSV file, messages from the IMAP mailbox are copied to the corresponding cloud-based mailbox until all the mailbox data is migrated. Microsoft Exchange processes up to N migration requests at one time, where N is the maximum number of simultaneous connections that the administrator specified for the migration.

    • It processes the migration requests for all the users included in the CSV file.

  6. After the initial synchronisation process and mailboxes are successfully migrated, the mailboxes in the IMAP messaging system and the corresponding cloud-based mailboxes are synchronised every 24 hours. This is called incremental synchronisation. This means that any new messages sent to the mailboxes on the IMAP server are copied to the corresponding cloud-based mailboxes. Incremental synchronisation continues until the administrator completes the overall migration.

    Note   During incremental synchronisation, deletions made in an on-premises mailbox are synchronised to the corresponding cloud-based mailbox. This means that if a user deletes an item from the on-premises mailbox that was previously migrated to the cloud, it will be deleted from the cloud-based mailbox.

  7. When the migration has finished running, Microsoft Exchange sends a status email message to the administrator. A migration is done when all migration requests are either completed or failed. The status email message includes links to the following CSV files:

    • MigrationErrors.csv, which contains information about each mailbox that failed migration. The administrator can fix these errors and resubmit a new CSV file.

    • MigrationStatistics.csv, which contains information about the number of items migrated from each on-premises mailbox.

  8. Additional migration batches and their corresponding CSV migration file are created and started, if necessary.

  9. After all mailboxes have been successfully migrated, the administrator updates the organisation's MX record to point to their cloud-based email organisation so that email messages are delivered directly to users' cloud-based mailboxes.

  10. After the change to the MX record has been propagated, the administrator completes the migration process. Microsoft Exchange does the following to complete the migration:

    • It runs a final synchronisation for all mailboxes. After this, email sent to the mailbox in the IMAP messaging system is no longer copied to cloud-based mailboxes.

    • It sends a final status email message after the migration is complete.

Note   As an alternative to using an IMAP migration to migrate mailbox items to cloud mailboxes, you could use the Microsoft Exchange PST Capture tool. PST Capture lets you search for and collect PST files on computers in your on-premises organisation and then import the PST files to cloud mailboxes. Note that you can also use PST Capture to import PST files to on-premises primary or archive mailboxes. For more information, see Microsoft Exchange PST Capture.

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Compare the types of migration

Which migration method is right for your organisation? It depends on your existing email organisation, how many mailboxes you want to migrate and whether you want to maintain mailboxes in your on-premises organisation.

Use the following table to decide what works for your deployment.

 

Existing organisation Number of mailboxes to migrate Do you want to maintain mailboxes in your on-premises organisation? Deployment option

Exchange 2010, Exchange 2007 or Exchange 2003

Fewer than 1,000 mailboxes

No

Cutover Exchange migration

Exchange 2007 or Exchange 2003

No maximum

Yes

Staged Exchange migration or hybrid deployment

Exchange 2010

More than 1,000 mailboxes

No

Hybrid deployment

Exchange 2010

More than 1,000 mailboxes

Yes

Hybrid deployment

Office 365 for professionals and small businesses

Fewer than 50 *

Not applicable **

Cutover Exchange migration

Live@edu

No maximum

Yes

Staged Exchange migration or IMAP email migration

Exchange 2000 Server or previous versions

No maximum

Yes

IMAP email migration

Non-Exchange on-premises messaging system

No maximum

Yes

IMAP email migration

* Office 365 for professionals and small businesses supports a maximum of 50 user mailboxes.

** Office 365 for professionals and small businesses doesn’t support directory synchronisation, which is required to maintain mailboxes in your on-premises organisation.

What is a hybrid deployment?

If you’re running Office 365 for enterprises and your long-term or short-term goal is to maintain mailboxes both in your on-premises organisation and in the cloud, you can deploy Exchange Online into your on-premises organisation in what is called a hybrid deployment. In a hybrid deployment, messaging functionality is seamless across the on-premises deployment and the cloud deployment. Features of a hybrid deployment include:

  • Moving on-premises mailboxes to the cloud with Mailbox Replication Service (MRS)

  • Mail routing between on-premises and cloud-based organisations

  • Unified global address list, also called a “shared address book”

  • Free/busy and calendar sharing between on-premises and cloud-based organisations

  • Message tracking, MailTips and multi-mailbox search between on-premises and cloud-based organisations

For more information, see Exchange Hybrid Deployment and Migration with Office 365.

 
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