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Mail Cutover Migration


Mail cutover migration is one of the methods used to migrate email from an on-premises Exchange server to Microsoft 365 or Office 365. It is designed for small to medium-sized businesses that want to move all their mailboxes to Microsoft 365 at once, as opposed to using staged or hybrid migration methods. Here's an overview of what mail cutover migration entails:

Key Features of Mail Cutover Migration

  1. Full Migration:

    • All mailboxes, distribution groups, contacts, and mail-enabled users are migrated in one go.
    • Suitable for organizations with fewer than 2,000 mailboxes, but Microsoft recommends this method for organizations with up to 150 mailboxes to reduce complexity and potential issues.
  2. Simplified Process:

    • It’s a straightforward migration process, making it easier for organizations with limited IT resources or expertise in Exchange Server and Microsoft 365.
  3. Pre-migration Tasks:

    • Verify that your domain is properly set up and configured in Microsoft 365.
    • Prepare your on-premises Exchange environment and ensure it meets the requirements for a cutover migration.
    • Create user mailboxes in Microsoft 365 before migration begins.
  4. Migration Process:

    • Configure Outlook Anywhere (RPC over HTTP) on your on-premises Exchange server.
    • Use the Exchange admin center (EAC) in Microsoft 365 to create a migration endpoint.
    • Create a cutover migration batch, which will start the process of copying mailbox data from the on-premises server to Microsoft 365.
    • Monitor the migration batch for errors and address any issues that arise during the process.
  5. Post-migration Tasks:

    • Assign licenses to users in Microsoft 365.
    • Update DNS records to point to Microsoft 365 for mail flow.
    • Ensure that users’ Outlook profiles are reconfigured to connect to Microsoft 365.
    • Decommission the on-premises Exchange server if it’s no longer needed.


  • Simplicity: Easier to manage since it's a one-time migration event.
  • Speed: Faster than staged or hybrid migrations since all data is moved at once.
  • Minimal Downtime: Users experience minimal downtime, typically just the time it takes to reconfigure their Outlook profiles.


  • Capacity Limits: Not ideal for organizations with more than 150 mailboxes due to the potential for increased complexity and risk.
  • Disruption: Since all users are moved at once, it may cause more significant disruption compared to staged migrations where users are moved in batches over time.

Ideal Scenarios for Mail Cutover Migration

  • Organizations with a small to medium number of mailboxes (preferably fewer than 150).
  • Businesses seeking to quickly and completely transition to Microsoft 365 without maintaining an on-premises Exchange environment.
  • Companies looking for a simpler, less technical migration approach with minimal ongoing maintenance requirements.

Mail cutover migration is an effective way for small to medium-sized businesses to move their entire email system to Microsoft 365 in one step, providing a straightforward and efficient transition with minimal downtime.

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