How to Migrate Emails from Office 365 Tenant to Tenant?

[benny01]

For Office 365 Tenant to Tenant Migration you need to be careful since it is a complex process, but following a step-by-step guide can help ensure a smooth transition. Here’s how you can perform a tenant-to-tenant email migration:

### Step 1: Prepare for Migration

#### 1.1. Assess and Plan
- **Identify Scope:** Determine the number of users, mailboxes, and data size to be migrated.
- **Create a Migration Plan:** Outline the migration timeline, key milestones, and potential risks.

#### 1.2. Gather Information
- **Source Tenant Details:** Collect information about the source Office 365 tenant, including domain names and user accounts.
- **Target Tenant Details:** Ensure you have administrative access to the target tenant and set up necessary domains.

### Step 2: Set Up the Target Tenant

#### 2.1. Add Domains to Target Tenant
- **DNS Verification:** Add your source tenant’s domain to the target tenant and complete the DNS verification process.

#### 2.2. Create User Accounts
- **User Provisioning:** Create user accounts in the target tenant matching those in the source tenant. Ensure usernames and email addresses are consistent.

### Step 3: Prepare Source Tenant for Migration

#### 3.1. Assign Roles
- **Administrator Roles:** Assign necessary administrative roles in both source and target tenants to ensure smooth migration.

#### 3.2. Create Migration Endpoints
- **Exchange Admin Center:** In the source tenant’s Exchange Admin Center, create migration endpoints to facilitate the transfer.

### Step 4: Choose a Migration Method

#### 4.1. Use a Third-Party Tool (Recommended)
- **Migration Tools:** Use reliable third-party migration tools like the Advik Office 365 to Office 365 Migration Tool for Windows. 
### Step 5: Perform the Migration

#### 5.1. Configure the Migration Tool
- **Source and Target Connections:** Set up connections to both the source and target Office 365 tenants in the migration tool.
- **Select Mailboxes:** Choose the mailboxes you want to migrate.

#### 5.2. Start the Migration
- **Initial Sync:** Run an initial sync to migrate data from the source to the target tenant. This process can take some time depending on the data volume.
- **Delta Migration:** After the initial sync, perform delta migrations to transfer any changes made during the initial sync.

### Step 6: Verify the Migration

#### 6.1. Post-Migration Checks
- **Verify Data:** Check that all emails, calendars, contacts, and other data have been accurately migrated to the target tenant.
- **Functionality Testing:** Ensure that email sending, receiving, and other functionalities work correctly in the target tenant.

### Step 7: Update DNS Records

#### 7.1. Change MX Records
- **DNS Settings:** Update the MX records to point to the new Office 365 tenant. This change might take some time to propagate.

### Step 8: Decommission the Source Tenant

#### 8.1. Finalize the Move
- **Switch Users:** Inform users to start using the new tenant.
- **Deactivate Source Accounts:** Deactivate or remove the old accounts from the source tenant to complete the process.

### Additional Tips

- **Communication:** Keep users informed throughout the migration process to manage expectations and reduce disruption.
- **Backups:** Ensure you have up-to-date backups of all data before starting the migration.
- **Testing:** Conduct thorough testing before and after the migration to ensure all data has been transferred correctly and services are functioning as expected.

By following these steps, you can effectively migrate emails and other data from one Office 365 tenant to another, ensuring minimal disruption to your organization.