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Summary: This article discusses two migration methods for transitioning from on-premises Exchange to Office 365: cutover migration and minimal hybrid migration. Cutover migration involves direct migration steps, while minimal hybrid migration is tailored for smaller businesses with specific requirements. Both methods have prerequisites and limitations, but a recommended tool is Kernel Migrator for Exchange – Express Edition for a comprehensive and versatile migration experience.

When transitioning from on-premises Exchange to Office 365, it’s important to understand the various migration methods at your disposal. Each method comes with its distinct advantages and constraints. If you are currently using the latest Exchange Server versions such as 2013, 2016, or 2019, the cutover migration is a suitable choice. On the other hand, if you require mailboxes to coexist in both the on-premises Exchange and Office 365 environments, the hybrid migration approach is the recommended path.

Minimal Hybrid Migration Method

Another noteworthy migration option tailored for small and medium-sized businesses is the minimal hybrid migration approach. This method comes into play when certain requirements are not needed, such as:

  • Automatic Retention of Archive Mailbox.
  • Automatic Outlook on the web redirection.
  • Activesync redirection for migrated users.
  • Cross-premises eDiscovery.
  • TLS secure mail flow for the communication between Exchange Server and Exchange Online.
  • Cross-premises Free/Busy.

Below are the essential prerequisites you should verify before proceeding with a minimal hybrid migration:

  • The version of the on-premises Exchange Server should be 2010, 2013, and 2016.
  • You are planning to move the mailboxes to Office 365 over a substantial amount of time.
  • You do not wish to continue to run the directory synchronization.

You can execute the migration in several consecutive phases, one at a time, if desired.

  1. Verify the domain ownership: The SMTP address of the on-premises Exchange Server should be same at the destination Office 365. So,
    You first need to verify the on-premises domain in Office 365.
    1. Sign in to Office 365 using account credentials.
    2. Go to Setup, then select Domains.
    3. Click ‘Add Domain’ button on the Domains page.
    4. On the ‘Add a Domain’ page, input the domain name of your on-premises Exchange Server. Click Next.
    5. At the ‘Verify domain’ page, there are two options among which you can make your selection. First one is ‘Sign in to GoDaddy,’ and another one is ‘Add a TXT record instead.’ The first option is for the domain associated with the and the second option for other registrars. Click Next.
    6. The TXT record file helps to verify the domain ownership. Follow the steps mentioned by your provider. Wait for at least 15 minutes to move to the next level.
    7. Go to Office 365 domain wizard, select ‘done,’ then choose ‘verify now.’ At the verification page, click Finish.
  2. Initiate Express Migration:
    1. Sign in to Office 365 with global admin credentials. Go to Setup and click Data Migration.
    2. Select Exchange option at the Migration page.
    3. At the Hybrid Configuration Wizard page, click Next and choose on-premises Exchange Server Organization. Choose the default values and click Next.
    4. Choose ‘User current Windows Credentials’ at the credentials page. Input the credentials of on-premises Exchange Server and Office 365 and click Next to validate the connection.
    5. At the ‘Office 365 Hybrid Configuration’ wizard, choose Minimal Hybrid Configuration and click Next.
    6. At the ‘Read for Update’ page, choose update to prepare the on-premises Exchange Server mailboxes for migration.
  3. Create users in Office 365 using directory synchronization:
    1. Click ‘Synchronize my users and passwords one time’ at the ‘User Provisioning’ page.
    2. Download and install the Azure AD Connect wizard. It synchronizes the on-premises Exchange Server with the Office 365.
    3. After successful installation, run the wizard and select the default settings for the Express Settings.
    4. After completing the synchronization, the wizard will take you to the Office 365 Data Migration page where you can see all the mailboxes synchronized with the Office 365.
    5. Finally, when the synchronization is complete, the directory synchronization is turned off for the Office 365 account.
  4. Provide Office 365 licenses to the users: Once you’ve successfully synchronized the credentials of the Office 365 user, the next step is to allocate Office 365 licenses. This crucial action ensures that the mailboxes are fully equipped to seamlessly receive mailbox items from your on-premises Exchange server.

    The Data Migration’s User Name List displays whether a license is necessary. Ensure that each user receives a complete license.

  5. Start the Mailbox Migration:
    1. Follow Setup >> Data Migration. At the Migration page, choose Exchange.
    2. Select the mailboxes at the Data Migration page and click the Start Migration option.
    3. The migration will start, and its status will be presented in the Migration Status.
  6. Update the DNS records: The DNS record relies on the MX record to determine the destination for email delivery. Throughout the migration process, the MX record was configured to direct email traffic to the on-premises Exchange Account. However, post-migration, it should be updated to route emails to the Office 365 account.

    Go to Office 365 Admin Center, follow Settings >> Domain and change the domain name.

    The streamlined hybrid migration approach adheres to the email synchronization and migration process.

Cutover Migration

The Cutover migration follows a different path and performs a direct migration. Here it is mentioned briefly.

  1. The Administrator verifies the domain ownership and informs the user about the impending migration.
  2. The Administrator creates empty mail-enabled mailboxes at Office 365 and prepares the on-premises mailboxes for migration.
  3. The Administrator creates the migration endpoint (it means a connection between on-premises Exchange and Office 365 is established).
  4. The Administrator starts the migration.
  5. After migrating the mailbox data, the Administrator provides the Office 365 license to the user.
  6. The Administrator routes the email messaging to Office 365.
  7. After completing the routing, the Administrator deletes the Cutover migration batch.
  8. The Administrator finishes the post-migration tasks and decommissions the Exchange Server.


Both migration methods are highly capable and proficient at facilitating smooth Exchange to Office 365 migrations. However, it’s crucial to acknowledge that they come with various prerequisites and limitations, which may render them unsuitable in certain scenarios. For a comprehensive migration experience that avoids any restrictions on mailbox quantities or compatibility with different Exchange Server versions, the ideal choice is Kernel Migrator for Exchange – Express Edition This versatile tool stands out as one of the most well-suited solutions for all your Exchange and Office 365 migration needs. Moreover, it excels in seamlessly migrating mailboxes between different Office 365 tenants, making it a versatile choice for any migration task.

Kernel Migrator for Exchange