Migration between two Office 365 tenants

When you start the program, you will see the Dashboard tab. Click Create a new migration job link on the How to start card. Select the source server type: Office 365. The Create Office 365 migration job wizard will open. Set the name of the job and click Next to go to the Mailbox types step. Here, select if you want to migrate primary mailboxes, archive mailboxes or both.

Proceed to the Source mailboxes step. If this is your first migration job, you will need to configure a connection to the Office 365 tenant that will be used as the source of your migration. Click Add new source connection in the Source server drop-down menu and a wizard will open. You need to complete these steps:

• Application registration – decide how you want CodeTwo Office 365 Migration to be registered in the Entra ID (Azure AD) of your source Office 365 tenant: automatically by the program (an account with the Global Administrator or Privileged Role Administrator role will be required) or manually by yourself. If you select the second option, you will be asked to provide the application registration details in the next step.
• Application details – enter the necessary application information. Additionally, you need to enter an email address of any user from your source Office 365 tenant. This account is used to gain access to the tenant's information, such as name, domain, etc.
• Configuration – this process registers CodeTwo Office 365 Migration in your Entra ID (if you have selected the Automatic registration option in the Application registration step) and configures the connection to the source Office 365 tenant.

If the configuration is successful, click Finish.

If any errors appear, see Troubleshooting

After successfully configuring the source connection, you will get back to the migration job wizard.

The Source mailboxes step now allows you to include or exclude mailboxes by using multiple filters. By default, the program includes All users along with the Public Folders as it is a most common scenario. Choose the mailboxes you want to migrate and proceed to the next step (Target mailboxes).

Now, set up a new target server connection by choosing Add new target connection from the Target server drop-down menu. A simple wizard will open:

• Application registration – decide how you want CodeTwo Office 365 Migration to be registered in the Entra ID (Azure AD) of your target Office 365 tenant: automatically by the program (an account with the Global Administrator or Privileged Role Administrator role will be required) or manually by yourself. If you select the second option, you will be asked to provide the application registration details in the next step.
• Application details – enter the necessary application information. Additionally, you need to enter an email address of any user from your target Office 365 tenant (this account is used to gain access to the tenant's information, such as name, domain, etc.). If you are migrating public folders as well, we recommend to use an email address of an admin account, as this account needs to have (or be assigned) the Owner rights to the root public folder and any subfolders, to which you will be migrating your source data. 
• Configuration – this process registers CodeTwo Office 365 Migration in your Entra ID (if you have selected the Automatic registration option in the Application registration step) and configures the connection to the target Office 365 tenant.

Once the configuration ends successfully, you will see green check marks. If any errors appear, see Troubleshooting.

After your connection is established, click Finish and proceed to the next step (Match mailboxes).

Matching the source mailboxes with the target mailboxes can be done automatically, by using the built-in automatch feature, or manually. We suggest that you start off by matching mailboxes automatically and modify the automatch settings if not all the mailboxes were matched in the first run. Use the manual option only if there are any mailboxes left unmatched after several automatch runs with a different configuration of the automatch mechanism.

To match mailboxes automatically, click the Match mailboxes button. In the window that opens, click Automatch > Automatch all mailboxes or select the mailboxes you want to match and click Automatch > Automatch selected mailboxes. Configure the automatching mechanism and click Automatch to start the matching process. If not all the mailboxes were matched, modify the automatch mechanism and run it again. Repeat this as many times as necessary.

Read more about the default configuration of the automatch mechanism and how to customize it

If any source mailbox is left unmatched despite several attempts to match it automatically with different automatch settings, match it manually.

If you are migrating public folders, make sure that the account used in the Target server connection wizard is the Owner of the root public folder and all subfolders to which you will be migrating your data. Learn more

Note that you can set the program to create target users and mailboxes in your Office 365 tenant, whether you’re matching mailboxes manually or automatically. Learn more

When you have matched all your mailboxes, save your configuration and close the matching window. Continue with the migration job wizard. The next steps will allow you to configure additional options.

You can configure the following additional options:

• Scheduler - this step allows you to set the job to be automatically started in the desired time periods, so you do not have to control it manually.
• Time filter - this filter is used to exclude items that are older or newer than a particular date.
• Folder filter - in this step you can completely exclude specific folders from the migration process.
• Advanced settings - this step lets you define how many mailboxes should be migrated at the same time and set the maximum size of items to be migrated.

Review your migration job in the Job summary step. Click Finish to close the wizard.

Move on to the JOBS tab and click Start on the toolbar to begin the migration. Once you start the migration, all items from the source mailboxes will be migrated to their corresponding target mailboxes.

If you notice any missing items in the target mailbox, restart the migration by using the Run delta migration option.

Once the migration is finished and you have noticed that some new items appeared in the migrated source mailbox, just restart the migration by using the Run delta migration option. Please keep in mind that this feature migrates only new items, not the modified ones. Delta migration can also be used to resolve issues with any items that failed to migrate on the first attempt.

If you plan to move your custom domain from the old Office 365 tenant to the new one, you first need to remove it from the former. To do so:

1. Log in to your Microsoft 365 admin center (Office 365 admin center).
2. Go to Settings > Domains.
3. Select the domain you want to disconnect.
4. In the window that opens, click Remove. If you are notified of any dependencies regarding the domain you intend to remove, simply confirm that you want to disconnect the domain.

You need to change your MX records to enable mail flow to the new server.  Additionally, you should also set up Autodiscover record to facilitate connecting migrated mailboxes with a mail client (e.g. Outlook). To change these DNS records manually, follow the steps below:

1. Log in to your Microsoft 365 admin center (Office 365 admin center).
2. Go to Settings > Domains, select your domain and click DNS Management.
3. Choose I’ll manage my own DNS records and click Next.
4. Select Exchange checkbox and click Next.
5. On this page, find the details regarding MX records and CNAME records (Autodiscover) that you need to use at your domain registrar. For specific instructions on how to configure DNS records in your domain registrar, visit this Microsoft page.
6. Once the DNS records have been configured, click Verify back in Office 365. Please note that it may take several hours for the changes to propagate.

If your Outlook has problems connecting to the new Office 365 tenant, you need to create a new Outlook profile for each user in your domain. You can do it using a GPO or Microsoft Intune.