How to migrate mailboxes between Office 365 tenants

No matter what the reason is, recently more and more companies decide to migrate their organizations to Office 365. And as the businesses operate in the cloud, companies more frequently look for the steps for a tenant to tenant migration, either within or between Office 365 organizations.

But surprisingly there is no convenient native way to perform this type of move. Even Microsoft suggests using a third party tool to accomplish this administration task. Having this in mind, I will show you how to easily migrate mailboxes between Office 365 tenants using CodeTwo Office 365 Migration.

Migrate mailboxes between Office 365 tenants

The video below explains the Office 365 tenant to tenant migration process in general. The article below goes into more detail, showing a tenant to tenant migration guide.

Before migration

Before you start the migration, make sure you have prepared your source and target serversdownloaded and installed CodeTwo Office 365 Migration as well as purchased a license* for all users you need to migrate from one Office 365 tenant to another.

Note: If you are migrating public folders too, keep in mind that they consume a number of 25 licenses of CodeTwo Office 365 Migration.

* If you want to test the software before purchasing it, you can try it out first – it’s free. The trial version works 30 days and you can use it to migrate up to 10 items per folder. Once you decide to use the program in a full version, simply activate the trial version with the license key you have purchased and continue with the migration process – all program settings will remain unchanged.

Configure CodeTwo Office 365 Migration

Once the program is installed and licensed, you can start the configuration of all program settings. First, let’s connect the program to source and target servers.

Set up a connection to the source Office 365 tenant

  1. Open the CodeTwo Office 365 Migration application. On the Dashboard tab, go to the Define source server connections card, and click the gear icon.Define source server connection to Office 365 tenant
  2. In the Manage source servers connections window, click the New button, and then Office 365 connection…
    new source server connection
  3. When the Office 365 source server connection wizard pops up, provide your Office 365 administrator credentials and click Next.
    Source server connection - providing admin credentials.
  4. To set up a connection with the source Office 365 server, click the Configure button.
    Configure source server connection to Office 365 organization.
  5. Once the source server connection is configured, click Finish.

Set up a connection to the target Office 365 tenant

To connect to the target Office 365 organization, follow the step below:

  1. On the Dashboard tab, go to the Define target server connections card and click the gear icon.
    Define the target server connection to Office 365 tenant.
  2. In the Manage target servers connections window, click the New button.
    New target server connection
  3. In the Target server connection wizard, provide an email address and password of the Office 365 administrator account. Click Next.
    New target server connection - providing Office 365 admin credentials
  4. Then, click Configure to set up the server connection to the target Office 365 tenant. Once it is complete, click Finish.
    Target server configuration finished

Configure a migration job

Now as the application is connected to both source and target Office 365 organizations, you can start the migration process. For this purpose, you need to create a migration job:

  1. On the Jobs tab, click the New button and select Migration job from Office 365…
    New migration job from Office 365 tenant.
  2. The Create Office 365 migration job wizard will open. In the Job name tab, provide the name for your migration job. Click Next.
  3. In the Source mailboxes tab, add mailboxes you want to migrate within this migration job. To add users click the Add button and to delete them use the Remove button. Here you can also manage the source Office 365 tenant connection, which is already set up. Click Next.

    Note: To migrate public folders to another Office 365 tenant, the application always consumes 25 licenses of CodeTwo Office 365 Migration (irrespective of public folders volume and a number of folders and subfolders). Make sure you have a sufficient number of licenses beforehand.Selecting Office 365 source mailboxes
  4. On the Target mailboxes tab, the target Office 365 tenant connection should be already set up (I’ve covered this at the very beginning of this instruction). If you want to change the target server connection to point to another Office 365 tenant, click the arrow in the Target server section and from the drop-down menu select Add new target connection….
    Add new target Office 365 server connection
  5. In the Match mailboxes tab, click the Match mailboxes button to open a new window where you can pair source and target Office 365 mailboxes. You can run the Automatch option or match mailboxes manually. For a manual selection, select a mailbox you want to match, click the drop-down menu in the Target user mailbox section and choose the option that suits you most. Click the Save button when you have finished and close the window.
    Match user Office 365 mailboxes
  6. In the Scheduler tab, you can specify activity periods of a migration job. I will leave this option unchecked to run migration manually later on. Click Next.
    Schedule activity periods
  7. If you want to narrow down the scope of migrated items, you can filter them by age in the Time filter. Click Next.
  8. In the Folder filter tab, specify which folders you want to migrate. Click Next.
  9. In the Advanced settings tab, set the number of mailboxes you want to migrate at the same time as well as the maximum size of migrated items. Click Next.
    Advanced settings
  10. In the Job summary tab, check whether all settings are correct. If yes, click Finish.

Migrate mailboxes between Office 365 organizations

Start the migration job

To start migration between Office 365 tenants, go to the Jobs tab. On the left pane, there is a list of migration jobs you have created – at this moment there is just one migration job.

A migration job ready to start.

Click your job name and then click the Start button in the top menu. The migration job will start right away.

Start the migration job

Monitor the migration

CodeTwo Office 365 Migration allows you to monitor the migration process from the very beginning to the end – separately for each migration job. The program reports its operations on mailboxes in real time. All statistics are displayed in the Jobs tab for currently selected migration job.

Migration between Office 365 tenants in progress

View migration reports

To view more detailed reports from the mailbox migration, go to the Reports section in the top menu of the program’s Jobs tab. There you can open Overall, Job and Mailbox reports. Here is an example of a Mailbox report:

Mailbox migration report

Run delta migration

If you have already finished the migration process between Office 365 organizations, but realized that there are some new emails in source mailboxes you need to migrate too, run the Rescan feature for the selected migration job:

Delta migration feature

This option allows you to safely run the migration process again to move only new emails to the target Office 365 tenant. No duplicates will be created as the application while rescanning mailboxes, searches only for new items. You can view migration reports to see whether new items were moved as well.

That’s it. Now the content of all source Office 365 mailboxes selected for migration is copied to mailboxes on a different Office 365 tenant. The source mailboxes remain untouched during the process so users can work without any interruption. In this example, I used just one migration job but the program allows to create numerous migration jobs depending on the individual company requirements – so this is where you can suit the program to your needs.

Suggested reading:

Tools for Microsoft 365

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