What you demand to know about a cutover electronic mail migration in Exchange Online

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As office of a Microsoft 365 or Office 365 deployment, you can drift the contents of user mailboxes from a source email system to Microsoft 365 or Office 365. When yous do this all at one time, it'southward called a cutover migration. Additionally, this migration method moves post users, mail contacts, and mail-enabled groups with their membership. Choosing a cutover migration is suggested when:

  • Your current on-premises Exchange organisation is Microsoft Exchange Server 2003 or after.

  • Your on-premises Exchange arrangement has fewer than 2,000 mailboxes.

    Note

    Even though cutover migration supports moving up to 2000 mailboxes, due to length of time information technology takes to create and drift 2000 users, it is more reasonable to migrate 150 users or less.

If a cutover migration won't work for you, see Ways to drift email to Microsoft 365 or Role 365 for other options.

Things to consider

Setting up an email cutover migration to Microsoft 365 or Part 365 requires careful planning. Earlier you brainstorm, here are a few things to consider:

  • You lot can move your entire electronic mail system to Microsoft 365 or Office 365 over a few days and manage user accounts in Microsoft 365 or Part 365.

  • A maximum of 2,000 mailboxes can be migrated to Microsoft 365 or Office 365 by using a cutover Exchange migration. However, it is recommended that you merely migrate 150 mailboxes.

  • The primary domain name used for your on-bounds Substitution system must be an accepted as a domain owned by you in your Microsoft 365 or Office 365 organisation.

  • Afterwards the migration is complete, each user who has an on-premises Substitution mailbox also will be a new user in Microsoft 365 or Function 365. Only you'll still accept to assign licenses to users whose mailboxes are migrated.

Bear on to users

After your on-premises and Microsoft 365 or Office 365 organizations are set up for a cutover migration, mail-setup tasks could impact your users.

  • Administrators or users must configure desktop computers: Make sure that desktop computers are updated and prepare up for use with Microsoft 365 or Office 365. These actions allow users to use local user credentials to sign in to Microsoft 365 or Role 365 from desktop applications. Users with permission to install applications can update and gear up their own desktops. Or updates tin be installed for them. Subsequently updates are fabricated, users can send email from Outlook 2013, Outlook 2010, or Outlook 2007.

  • Potential filibuster in e-mail routing: Email sent to on-bounds users whose mailboxes were migrated to Microsoft 365 or Office 365 are routed to their on-premises Exchange mailboxes until the MX record is inverse.

How does cutover migration work?

The primary steps you perform for a cutover migration are shown in the following illustration.

Process for performing a cutover email migration to Microsoft 365 or Office 365.

  1. The administrator communicates upcoming changes to users and verifies domain buying with the domain registrar.

  2. The ambassador prepares the servers for a cutover migration and creates empty mail service-enabled security groups in Microsoft 365 or Office 365.

  3. The administrator connects Microsoft 365 or Role 365 to the on-premises email organization (this is called creating a migration endpoint).

  4. The ambassador migrates the mailboxes and then verifies the migration.

  5. Grant Microsoft 365 or Part 365 licenses to your users.

  6. The administrator configures the domain to brainstorm routing electronic mail directly to Microsoft 365 or Office 365.

  7. The administrator verifies that routing has changed, and then deletes the cutover migration batch.

  8. The administrator completes post-migration tasks in Microsoft 365 or Part 365 (assigns licenses to users and creates an Autodiscover Domain Name System (DNS) record), and optionally decommissions the on-premises Exchange servers.

    Run into how-to steps in Complete mail migration tasks.

  9. The ambassador sends a welcome letter to users to tell them nearly Microsoft 365 or Office 365 and to draw how to sign in to their new mailboxes.

Ready to offset?

If you're comfortable setting up a migration to Microsoft 365 or Office 365, here are the tasks that need to be washed:

  • Set up Exchange Server by using the Exchange admin heart.

  • Alter your organization'south MX record to bespeak to Microsoft 365 or Office 365 when the migration is consummate. Your MX tape is how other mail systems find the location of your electronic mail system. Irresolute your MX tape allows other post systems to begin to ship e-mail directly to the new mailboxes in Microsoft 365 or Office 365. Nosotros provide instructions on how to practice this for many DNS providers. To fix your public DNS servers, you need to change your arrangement'south MX tape to point to Microsoft 365 or Part 365 if you choose to route all incoming internet mail service for your on-premises Commutation organization through Microsoft 365 or Function 365.

If you're fix to begin a cutover migration, go to Perform a cutover migration of email.

See also

Ways to migrate email to Microsoft 365 or Office 365

Use PowerShell to perform a cutover migration