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Summary: The article discusses the benefits of migrating from on-premises Exchange Server to Office 365, focusing on staged migration. It outlines the steps required for a successful migration, including domain verification, CSV file creation, and batch setup. The article suggests that while staged migration is effective, it requires technical expertise and recommends using Kernel Migrator for Exchange for a smoother migration experience.

A savvy business strives to trim its expenditures while preserving essential advantages. Office 365 offers the same advantages as an on-premises Exchange Server while maintaining cost-efficiency. Beyond its cost-effectiveness, Office 365 boasts numerous benefits that go beyond what on-premises Exchange can provide. This includes seamless access to a suite of additional services such as SharePoint Online, OneDrive for Business, Yammer, and expanded cloud storage capacity, all without the need for additional hardware investments.

Staged migration from Exchange to Office 365

Microsoft has streamlined the process of migrating user mailboxes from on-premises Exchange to Office 365 by providing a range of efficient migration methods. When you opt to migrate mailboxes in batches, this approach is known as staged migration. Staged migration is particularly effective in the following scenarios:

  • When the mailboxes are more than 2,000.
  • When you are migrating from Exchange Server 2003 and 2007.

Upon the successful migration process, the existing mailboxes will undergo a transformation into mail-enabled accounts. Subsequently, users will need to establish an Office 365 profile within their Outlook application. Once configured, Outlook will seamlessly establish connections with these accounts. However, it’s important to note that while a staged migration is adept at transferring user mailboxes, migrating the arbitration mailbox from Exchange 2010 to 2016, necessitates a distinct migration strategy.

Prepare Exchange Server for a staged migration
  • You should configure Outlook Anywhere on the on-premises Exchange Server system as the migration service will require it to connect to the Server.
  • The account you will use for mailbox migration should have adequate permissions to access the mailboxes. These permissions are WriteProperty, TargetAddress, and Receive As.
Verify the domain in Office 365

In order to successfully migrate mailboxes from an on-premises Exchange Server to Office 365, it is essential to have the identical business domain registered within Office 365. Therefore, it is imperative to confirm your ownership of this domain within the Office 365 environment.

  1. In the Office 365 admin center, go to Setup>Domains>Manage domains>Add domain.
  2. Input the Exchange Server domain name and confirm that you own the domain by following the general instructions.
  3. Your DNS service provider will help you in verifying the details using TXT records.
  4. After completing the verification, you can click Finish and close the wizard.

The verification process is a crucial step in any staged migration, as it serves to confirm your domain ownership within Office 365 as well.

Create the CSV file for migration

Once you have confirmed the validity of the domain name and determined the specific mailboxes you intend to migrate, you can proceed by generating a new CSV file containing pertinent information about the on-premises mailboxes.

Three attributes are necessary for this process: Email Address, Password, and Force Change Password. Below is a fundamental example of a CSV file:

Create a migration endpoint to connect to Office 365

The migration endpoint has all the required information of the settings/credentials to connect Exchange mailboxes to Office 365. The migration endpoint is also used to start the migration batch.

  1. In the Exchange admin center, go to recipients>migration>more>migration endpoints.
  2. Choose New to create the endpoint.
  3. input the email address, account with privilege, and password of an account with privileges.
  4. Check that the connection is verified.
  5. Input a migration endpoint name and click New to create the endpoint.
Create a new staged migration batch in Exchange Admin Center
  1. In Exchange Admin Center, go to Migration>Batch>New migration batch>Migration onboarding.
  2. Choose Staged Migration as the desired migration type. Click Next.
  3. In the Set endpoint section, choose the migration endpoint that you have created in the previous step.
  4. Upload the CSV file that you have created along with all mailbox information.
  5. Schedule batch migration, check and verify all the details and save them.
Start the batch for a staged migration
  1. In the Exchange Admin Center, go to Migration and choose Batch. Select the batch that you have created and click Start Migration.
  2. When the batch starts working successfully, then its status will be changed to syncing.
Delete the staged migration batch

After successfully completing the migration, you can promptly verify the contents within Office 365 and access them without delay. At this point, it is safe to proceed with the deletion of the staged migration batch.

Navigate to the Exchange Admin Center and access the “Migration and Batch” section. Within the batch dashboard, select the batch that has finished processing, and proceed to remove it by clicking on the “Delete” option. Once the migration process is successfully concluded, you can proceed to configure new Office 365 accounts in Outlook. In case the AutoDiscover is not working for setup Office 365 account, consider configuring it manually.

A staged migration offers an effective method for transferring mailboxes from an Exchange Server to Office 365. However, it can be quite time-consuming and necessitates several manual steps before you can initiate a straightforward batch migration. This process is best suited for individuals with substantial technical expertise in Exchange Server. Alternatively, you may opt for a reliable Exchange Migrator software solution to seamlessly migrate your on-premises Exchange to Office 365.


Kernel Migrator for Exchange stands out as the ultimate solution for fulfilling Exchange migration needs across diverse businesses. This exceptional tool not only expedites the migration process but also offers a broader compatibility range. While Exchange staged migration is restricted to migrating solely Exchange 2003 and 2007, Kernel Migrator can seamlessly transfer mailboxes from all Exchange Server versions, ensuring a comprehensive solution that seamlessly integrates with all Office 365 plans.

Kernel Migrator for Exchange