Planning and Deployment
Planning for service changes and growth
Organizations should choose migration options based on their source email systems, the desired end state (fully hosted or partially hosted), the number of users to migrate, and how quickly the end state needs to be reached.
Cloud-only deployment Your organization has all user mailboxes hosted in Exchange Online.
Exchange hybrid deployment Your organization has some user mailboxes hosted in an on-premises Exchange organization and some user mailboxes hosted in Exchange Online.
A cloud-only deployment is one where your organization in the Exchange Online service isn't connected with an on-premises Exchange organization. All users and mailboxes are hosted and managed in Exchange Online and Office 365.
Available for Microsoft Exchange 2003, Exchange 2007, Exchange 2010 and Exchange 2013 on-premises organizations, a hybrid deployment offers either a long-term coexistence configuration with some mailboxes hosted on-premises and some mailboxes hosted in Exchange Online or a migration path to hosting all user mailboxes in Exchange Online. A hybrid deployment offers organizations the ability to extend the feature-rich experience and administrative control they have with their existing on-premises Microsoft Exchange organization to the cloud. Hybrid deployment features include secure mail transport, shared calendar free/busy information, and message tracking between the on-premises and Exchange Online organizations.
For more information about hybrid deployments, see Exchange Server 2013 Hybrid Deployments. If you are using Office 365 operated by 21Vianet, see Configuring Exchange hybrid deployment features with Office 365 operated by 21Vianet.
On-premises Exchange 2003 organizations must install at least one Exchange 2010 Client Access/Mailbox server to configure a hybrid deployment with Exchange Online. On-premises Exchange 2007 organizations must install at least one Exchange 2010 or Exchange 2013 Client Access and Mailbox server to configure a hybrid deployment with Exchange Online. On-premises Exchange 2010 and Exchange 2013 organizations natively support hybrid deployments with Exchange Online. For more information about Exchange server compatibility in hybrid deployments, see Hybrid Deployment Prerequisites> On-premises Exchange organizations must configure their organization for a hybrid deployment. We strongly recommend that administrators use the Exchange Server Deployment Assistant and the Hybrid Configuration Wizard to configure the hybrid deployment. Learn more at Exchange Server Deployment Assistant
Organizations should choose migration options based on their source email systems, the desired end state (fully hosted or partially hosted), the number of users to migrate, and how quickly the end state needs to be reached. Possible migration options are:
IMAP migration Migrate mailbox data from IMAP-based email systems to Exchange Online.
Cutover Exchange migration Migrate mailboxes from Exchange Server 2003, Exchange Server 2007, Exchange Server 2010, Exchange 2013 and Hosted Exchange systems to Exchange Online in a single cutover migration.
Staged Exchange migration Perform a staged migration to migrate mailboxes from Exchange Server 2003 or Exchange Server 2007 with web-based migration tools and minimal changes to on-premises infrastructure.
Remote move migration Migrate on-premises Exchange mailboxes to Exchange Online in an Exchange hybrid deployment. You must have an Exchange hybrid deployment to use a remote move migration.
For more information about migrating email and mailboxes to Exchange Online, see Mailbox Migration to Exchange Online .
Exchange Online offers a web-based tool for migrating mailbox data from email systems that support IMAP. It guides administrators through the following migration steps:
Create empty mailboxes in the cloud for users in the organization (typically this is done by uploading a .csv file or using remote Windows PowerShell).
Enter the remote server connection settings.
Use a CSV file to specify the mailboxes whose data will be migrated to Exchange Online mailboxes.
After this information is entered, Exchange Online begins to migrate mailbox content via IMAP (calendar items, contacts, tasks, and other non-mail items are not migrated).
For more information about IMAP migration, see Migrate Email from an IMAP Server to Exchange Online Mailboxes and Migrate other types of IMAP mailboxes.
To avoid overusing the remote server's resources and bandwidth during the migration, Exchange Online creates fewer than 10 connections to the IMAP server.
Cutover Exchange migration
Exchange Online offers a web-based tool for migrating data from on-premises Exchange Server 2003, Exchange Server 2007, or Exchange Server 2010 environments. It guides an administrator through the following migration steps:
Using the email address and credentials for an on-premises administrator account, Exchange Online connects to the on-premises email organization by using the Autodiscover service.
Exchange Online uses an RPC/HTTP connection to read directory information from the remote server and create mailboxes in Exchange Online.
Exchange Online synchronizes the mailbox content to the cloud mailboxes. Users remain connected to their original mailboxes while their data is being migrated to Exchange Online.
After the initial migration is complete, any changes are synchronized to the cloud every 24 hours until the administrator stops or deletes the migration batch.
To switch users to their cloud mailboxes, administrators configure their MX record to point to Office 365 and reconfigure the users' profiles in Outlook. When users switch to their cloud mailboxes, their local offline folders (.ost files) will resynchronize, resulting in the download of migrated mail to the client workstation. Users can reply to old messages in their mailboxes after migration.
For more information about a cutover Exchange migration, see What you need to know about a cutover email migration to Office 365.
An organization can migrate a maximum of 2,000 Exchange 2003, Exchange 2007, Exchange 2010, or Exchange 2013 mailboxes to the cloud using a cutover Exchange migration. > Exchange Online must connect to an on-premises Exchange Server, so the on-premises server must have a certificate issued by a trusted certificate authority and a public IP address.
Staged Exchange migration
With a staged migration, users can be migrated to the cloud using the web-based Exchange migration tool and the Directory Synchronization tool. Instead of migrating all users at once, like a cutover Exchange migration, administrators migrate users in batches. This is accomplished by uploading a .csv file to specify a partial list of users to migrate. In a staged migration, all of the users in an organization can share the same email domain name.
Staged Exchange migration requires administrators to use the Online Services Directory Synchronization tool. This provides users with a unified Global Address List (GAL) where the online environment is continuously synchronized with the on-premises environment.
For more information about staged Exchange migrations, see What you need to know about a staged email migration.
Organizations can't use a staged Exchange migration to migrate Exchange 2010 and Exchange 2013 mailboxes. If you have fewer than 2,000 Exchange 2010 or Exchange 2013 mailboxes in your organization, you can use a cutover Exchange migration. If you have more than 2,000 Exchange 2010 or Exchange 2013 mailboxes, you can implement a hybrid deployment. > During migration, administrators must use the Online Services Directory Synchronization tool to provide users with a unified Global Address List where the online environment is continuously synchronized with the on-premises environment.
Microsoft provides several tools to help migrate an existing email environment to Exchange Online. Which ones are appropriate depends on the organization's current environment and deployment goals:
Migration dashboard Administrators can use the Migration dashboard in the Exchange admin center to manage mailbox migration to Exchange Online in a cutover or staged Exchange migration. Administrators can also use the dashboard to migrate the contents of users' mailboxes from an on-premises IMAP server to existing Exchange Online mailboxes. The dashboard gives administrators the following capabilities:
Create and start multiple migration batches Administrators can create and queue up to 100 migration batches. Only one migration batch runs at a time, but administrators can queue up multiple batches, so when a migration batch is finished running the next batch in the queue starts.
Restart a migration batch with failures After the initial synchronization for a migration batch, where items are copied from on-premises mailboxes to the cloud mailboxes for each user in the migration batch, some mailboxes may fail synchronization. Administrators can restart that migration batch to try to synchronize the failed mailboxes.
Get details about skipped items For IMAP migrations, cutover migrations, and staged migrations, the Migration dashboard displays information about the specific items that were skipped, including the reason why and where the item is located in the user's mailbox.
Open migration reports Administrators can open migration statistics or the migration error report for a migration batch right from the dashboard.
Edit a migration batch If a migration batch for a staged Exchange migration or an IMAP migration is in the migration queue but not currently running, administrators can edit the migration batch.
Azure Active Directory Sync tool The Azure Active Directory Sync tool plays an important role in migration to hybrid email scenarios that utilize both Exchange Online and an on-premises Exchange Server. The tool performs a one-way synchronization from on-premises Active Directory to Exchange Online. After migration is complete, administrators only need to use Exchange Online to manage Active Directory users and groups. The tool also provides users with a unified Global Address List where the online environment is continuously synchronized with the on-premises environment.
For more information about the Azure Active Directory Sync tool, see Directory synchronization: Roadmap.
Hybrid Configuration Wizard The Hybrid Configuration Wizard streamlines the hybrid deployment process by simplifying the on-premises and Exchange Online configuration of features and services. Introduced as part of Exchange Server 2010 Service Pack 2, the Hybrid Configuration Wizard is run only in on-premises organizations and has the following components:
An Exchange admin center (EAC) wizard that guides administrators through the end-to-end process for configuring a hybrid deployment.
A set of Exchange Management Shell (EMS) commands that orchestrate the configuration process.
For more information about the Hybrid Configuration Wizard, see Hybrid Configuration Wizard.
Remote Windows PowerShell As part of the Exchange Online December 2011 Service Update, remote Windows PowerShell can be used to help troubleshoot migration errors. For instance, administrators can display diagnostic information for migration batches, as well as migration statistics and diagnostic information for users based on their primary SMTP addresses.
To view feature availability across Office 365 plans, standalone options, and on-premise solutions see, Exchange Online Service Description.
We'd love to hear your thoughts. Choose the type you'd like to provide:
Our feedback system is built on GitHub Issues. Read more on our blog.