How to Perform Office 365 Tenant-to-Tenant Migration Step by Step

Overview
Office 365 tenant-to-tenant migration involves transferring your Office 365 content from one tenant account to another. This process is commonly required during mergers, acquisitions, or company rebranding. However, Microsoft does not provide a direct solution to migrate data between tenants. Therefore, proper planning and the use of reliable tools are essential for a successful migration. In this article, we will discuss effective migration methods, including the Aryson Email Backup Wizard for quick and safe migration.

Major Reasons for Office 365 Tenant-to-Tenant Migration

There are several scenarios where an organization may need to perform a tenant-to-tenant migration:

• Mergers and Acquisitions: Consolidating data from multiple organizations during mergers or acquisitions.

• Business Unit Migration: Moving an individual department or business unit to a new tenant.

• Domain Rebranding: Adopting a new domain during company rebranding.

• Tenant Consolidation: Combining multiple tenants into a single centralized tenant.

• Compliance Requirements: Ensuring adherence to organizational or regulatory compliance standards.

Proven Methods for Office 365 Tenant-to-Tenant Migration

The two most effective approaches for migrating Office 365 data are:

1. Automated Software

2. Manual Method

Method 1: Using Software for Microsoft 365 Tenant-to-Tenant Migration

Migrating data manually between two Office 365 tenants can be overwhelming, especially for beginners. To simplify this process, the Email Backup Wizard is an excellent choice. This software enables users to transfer large volumes of Office 365 data between tenants without any data loss. Key features include:

• Preservation of attachments, folder structure, and metadata.

• Reduction of human errors with cross-verification of selected files.

• Customization options such as removing duplicate emails and filtering by date range.

• Flexibility to migrate Office 365 data to Google Workspace, Thunderbird, AOL, and Yahoo Mail.

Step-by-Step Guide Using Email Backup Wizard:

1. Open the Email Backup Wizard and select Office 365 as the source.

2. Enter admin credentials for the source tenant and log in.

3. Choose the mailboxes you want to migrate.

4. Select Office 365 as the target from the “Migrate in Email Client” dropdown.

5. Enter credentials for the target tenant and log in.

6. Apply any built-in filters if needed, then proceed with the migration.

Note: This method enables tenant-to-tenant migration within a few clicks. If you prefer manual migration and have technical knowledge and time, you can follow the steps below.

Method 2: Manual Office 365 Tenant-to-Tenant Migration

Manual migration involves two main stages:

1. Pre-Migration Stage

2. Office 365 Migration Stage

Stage 1: Pre-Migration

Step 1: Domain Preparation

• Ensure the target tenant has all necessary licenses.

• Set up admin accounts in both source and target tenants.

• Grant global admin access to both tenants.

• Configure user and resource mailboxes, and export distribution groups in the target tenant.

• Consolidate Active Directory domains and synchronize with the target tenant if required.

• Inform users about potential downtime and password changes.

Step 2: Domain Verification

• Verify the target tenant domain in Microsoft 365.

• Add necessary TXT DNS entries and configure the source domain in the target tenant.

• DNS changes may take 15 minutes to 24 hours depending on TTL values.

• Avoid changing MX records at this stage to prevent mail disruption.

Step 3: Migration Planning

• List all mailboxes to migrate and create a mapping CSV file (required if using PowerShell or third-party tools).

• Identify the lowest TTL value for your domain’s MX record and plan downtime.

• Reduce MX record TTL to 24–48 hours before migration.

• Disable directory synchronization to prevent updates during migration.

• Disable Azure AD Connect if using on-premises Active Directory.

Stage 2: Office 365 Tenant-to-Tenant Migration

Step 1: Control Incoming Mail

• Pause incoming emails to the source tenant by modifying the MX record or using third-party software.

Step 2: Prepare the Source Tenant

• Change all previous email addresses to the default Office 365 domain.

• Update primary SMTP addresses to the onmicrosoft.com domain.

• Remove Lync/Skype licenses and, if necessary, Teams licenses.

• Reset distribution lists and resources to their respective domains.

• Remove secondary emails linked to the migrating domain.

• Verify using PowerShell that no objects are still associated with the source domain.

Step 3: Prepare the Target Tenant

• Configure the autodiscover CNAME record.

• Authenticate new domains if AD FS is used.

• Activate new user accounts and assign licenses after mailbox creation.

• Set the source domain as the primary email domain and share new credentials.

• Update the MX record to point to the target tenant and redirect mail flow.

• Test email delivery to ensure proper sending and receiving.

Conclusion

This blog covered two methods for Office 365 Tenant-to-Tenant Migration. The automated software approach allows quick migration within a few clicks, while the manual method requires technical expertise and careful configuration. Organizations can choose the approach that best suits their requirements, resources, and technical proficiency.