How to Migrate Mailboxes from One Tenant to Another in Office 365?

Himanshu Goyal    Himanshu Goyal     Updated On - 14 Aug 2019

Sometimes Office 365 administrators need to migrate mailboxes from one tenant to another, but they don’t find any suitable ways for it. Though there are some manual approaches, they are very complex, and you won’t be able to perform it without proper guidance and technical knowledge. Many queries related to this can be found in Microsoft’s forums too.

So, here we are going to discuss some basics that can help you migrate mailboxes from one Office 365 tenant to another. Also, here we’ll talk about how you can plan the migration.

A Simple Approach to Office 365 Tenant to Tenant Migration

The Office 365 tenant to tenant migration is performed using PowerShell scripts or third-party tools. Before that, there is an Office 365 Pre & Post Migration checklist you should keep in mind.

Pre-migration Stage

Domain Preparation

Prepare the domain with the following steps:

  • Ensure that you have enough licenses for the target Office 365.
  • Create admin accounts in both the source and target to perform the migration smoothly.
  • Create user mailboxes, room/resource mailboxes, and distribution groups in the target.
  • If needed, perform AD DS consolidation using AD DS tools and sync source domain with the target domain manually or using synchronization.
  • Train your end users regarding the post-migration use of Office 365.
Domain verification
  • Start verification of target tenant domain in Office 365.
  • Add a source domain in the target Office 365 admin center and create TXT records in DNS.
  • Make sure the domain is in use only one tenant. Otherwise, the verification will fail.

  • After performing these steps, it will take around 72 hours for the change to be seen.
Migration Scheduling
  • Generate a list of user mailboxes that are to be migrated and create a CSV file for mapping.
  • Note the lowest value of TTL on MX record (of the primary email domain).
  • Disable directory sync for source tenant (from Office 365 admin center).

Migration Stage

Stop inbound mail flow

Stop inbound mail flow to the source tenant by changing the primary MS record to an unreachable value or by using a third-party service. As you have noted the lowest value of TTL on MX record (of primary email domain) in your preparation step, you can plan the time of this step easily.

Source tenant preparation

Before moving the Office 365 mailbox to another tenant, the primary mail domain should be erased from all objects in the source tenant.

Preparing the target domain

It involves the verification of source tenant in the target domain (do one hour after the previous step).

  • When you use AD FS, you’ll have to configure a new domain in target tenant for AD FS.
  • Activate the new user accounts in the target domain and assign licenses.
  • On the new users, set the source domain as the primary email address (done using Windows PowerShell). Also, decide on communicating the passwords to end users.
  • Now you can route the emails to the new mailboxes.
  • Test the mail flow in and out of the target tenant.

Now it is time to decide on the migration method. You can also decide on the type and amount of data to be migrated. Migration can be accomplished using PowerShell scripts. However, third-party migration tools are recommended as they offer complete control over the migration.

Kernel Office 365 Migration tool – For a quick and easy tenant to tenant migration

Kernel Office 365 Migration is an advanced tool that is specially designed for the Office 365 tenant to tenant migration. It allows users to easily migrate every Office 365 mailbox from one tenant to another. It has some amazing features that make it the best migration tool for Office 365.

  • Migrates from one Office 365 tenant to another without any hassles
  • Allow migration of multiple mailboxes from one tenant to another
  • Migrate unlimited user mailboxes with a CSV file
  • Offer specific filters to migrate selective data
  • Save migration report in CSV format after complete migration

Download Now

Let’s have a look at the working process of this tool:

  1. After installation, launch software on your system.
  2. From the home screen, click Add Source to add first tenant Office 365 account as the source.
  3. The Office 365/Exchange window appears on the screen, enter the Office 365 account details, and select List all mailboxes using above credentials. Now, hit the Get User mailboxes button. All the Office 365 mailboxes will appear in the tab, select the specific mailboxes, and then click Add.
  4. Once mailboxes are added to the source section, click Add in the Add Destination section to add another Office 365 tenant as the destination.
  5. Just as with the source section, provide credentials in the destination section for Office 365 account. Make sure you add all the mailboxes for accurate migration.
  6. After adding both the source and destination mailboxes, map mailboxes to each other and then click Set Filter and Migrate.
  7. In the next step, select the type of destination (Mailbox, Public Folder, Archive Mailbox) and click Migrate.
  8. The Filter Selection window will pop up on the screen; apply filters to the mailboxes if you want to, and click I am OK Start Migration.
  9. The tool will start migrating mailboxes from one tenant to another. Once the migration is done, a notification will appear on your screen confirming the same, click OK to finish the process.

The migration report can be saved in a CSV format. This way, you can quickly perform Office 365 tenant to tenant migration using Kernel Office 365 Migration.

Conclusion

The manual approach of moving mailboxes from one Office 365 tenant to another is very complicated, as it is based on PowerShell scripts. Not every user is capable of using the Shell Scripts because it requires technical expertise. So, Kernel Office 365 Migration is the best option that allows you to move Office 365 mailboxes from one tenant to another. Even non-technical users can easily migrate their Office 365 data using this tool.

Download Now