This Post explains how to migrate mailboxes from one Office 365 tenant to another Office 365 tenant.
There is no straightforward native method that would easily walk you through the migration process between Office 365 organizations. The manual migration will be risky and time consuming process therefore, to migrate email from one Office 365 tenant to another, it is better to get a third party migration tool.
Below tools can be considered to complete the migration activates.
- Cloud Migrator 365
- CodeTwo Office 365 Migration
- Sys Tools office 365 to office 365 Migrator
All tools will follow similar process to complete the migrations. Few tools will operate from cloud and other required a tool installation.
Follow the migration process as bellow.
- If required to use the custom domain, the domain should be registered on the target office 365 domain.
- If source and target domains are different then it we should add source domain to the target domain and complete the verification by adding TXT records to the source domain server. The process will not be success because the domain is already attached with other server. After Migration once we detach the source server then the process get success.
- If the source and target domains are different, Means if source is xyz.com and destination is abc.com then the users should be created in the destination domain before migration
- Assign required licenses to the users.
- Make sure that the admin account used to connect to the source Office 365 tenant has the necessary roles assigned and that it has its mailbox configured correctly and ensure that this account is mailbox-enabled.
- Make sure that the admin account used to connect to the target Office 365 tenant has the necessary roles assigned and that it has its mailbox configured correctly and ensure that this account is mailbox-enabled.
- Make sure the target Office 365 administrator’s email address corresponds to a right domain
Assuming that your custom domain has already been added to the target Office 365 (see Step 1 above) or that you use a default target *.onmicrosoft.com domain, double-check that your target admin’s email address is correct and corresponds to the domain you will be migrating to. To do that, perform the following actions:
- Log in to the target administrator’s Office 365 account.
- Go to Office 365 admin center.
- Choose Users > Active users from the menu on the left. The table with all organization users will be displayed.
- Select the administrator’s account and check in the User name / Email section if the address corresponds to the right domain.
- If not, click Edit, locate the drop-down menu that contains all available domains within your organization, and select the domain you will be migrating to. Save the changes.
- Prepare the
source mail boxes for migration-
- Impersonate the mail boxes
From Exchange Admin Center open Admin Roles and edit the Discovery Management Role, add Application Impersonation Role to the Roles List and add admin to the Members List
- Prepare the Destination mail Boxes
From Exchange Admin Center, Open Recipients and under mail boxes click on “…” and Set Default message box size restrictions to maximum. This can be rest to the original value after migration.
- Install the migration tool to a computer with good configuration and better network speed.
- Get required license for the migration tool.
- Connect to the source server using the admin credentials and validate the user using the migration tool. Complete the tool initial configuration according to the tool manual.
- Select the source mail boxes to migrate. The tools will allow to apply multiple filters to include and exclude the mail boxes. Also most of the tools support to import users from CSV file.
- Connect to the destination server and complete the required configurations
- Import the destination users from CSV or Add using tool options. Tools also support to create users in destination according to the source.
- Complete the source user and destination user mapping.
- Customize all
necessary aspects of migration Job- Options may change according to the tool.
- 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 may 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.
- Perform a test migration if tool support it
- Once test migration is success the migration process can be started.
- Check if the number of items migrated in the target mailboxes matches the number of items in the source server mailboxes
Check if there are any new items in the source mailbox after migration, if any new items existing in the source mail box restart the migration process with appropriate options.
- Run Migration on a dedicated high configured PC if the tool required an on premise installation.
- Perform mx record cutover migration over week end, Next working day the new mail boxes will be ready to use
- If number of
users are more or total mail box size is large the migration will not complete
over week end so should consider Perform a staged migration
- The migration process will start two week prior to the MX record cutover and will migrate all old mails first
- Once the old mails are successfully migrated to the new system we can perform an mx record cutover migration to complete the migration and then users can start using the new mail box.
- Alternatively we can perform a MX Record cutover migration first and migrate only last 90 days mails first and then old mails can be synced to the new mail box.
- More Number of migration Jobs can be created to improve the migration speed
- Monitor the migration process and check and find the reason for the error
- If any mail boxes failed to sync then rectify the error by checking the error log and migration report and restart the migration for the failed mail boxes.
- MX Record Change Over
- Change your MX records to enable mail flow to the new server. Please note that this process may take several hours.
- If any new items appear in a source mailbox while the MX records are being changed, it is possible to migrate them after the records setup process is completed. This can be done via the Rescan feature available in the Administration Panel of the program
- Disconnect the previous domain.
Remove the old domain from the system. If any issue occurred the Domain Provider will support to complete the changeover.
The Migration process may take one or two week to complete according to the mail box sizes and data transfer speed. For a safe migration follow staged migration and after migration detach the source server.
If there is more than 500 users to migrate or a large amount of SharePoint data to migrate, it’s a good idea to work with an Office 365 partner.