How to Migrate Exchange to Microsoft 365 Using Minimal Hybrid Configuration

Before starting the migration, you need to verify that you own the domain in Microsoft 365. This establishes trust between your on-premises environment and the cloud.

Navigate to the Microsoft 365 Admin Center at admin.microsoft.com and sign in with your Global Administrator account. Go to Settings > Domains and click Add domain.

Enter your on-premises domain name (e.g., contoso.com) and follow the verification wizard. You'll need to add a TXT record to your DNS provider:

TXT record: MS=ms12345678
Host: @ (or leave blank)
TTL: 3600

After adding the DNS record, return to the Admin Center and click Verify. The verification process typically takes 5-15 minutes.

The Exchange Hybrid Configuration Wizard (HCW) is the primary tool for setting up minimal hybrid configuration. Microsoft updates this tool regularly, so always download the latest version.

In the Microsoft 365 Admin Center, navigate to Setup > Data migration. Select Exchange as your migration source, then click Download application to get the latest HCW.

Run the downloaded installer on your domain-joined computer. The installer will download and launch the wizard automatically. Make sure you're running as an administrator:

Right-click on HybridConfigurationWizard.exe
Select "Run as administrator"

On the welcome screen, click Next to begin the configuration process.

The wizard needs to connect to your on-premises Exchange server to prepare it for migration. It will automatically detect your Exchange organization settings.

On the On-premises Exchange Organization page, the wizard will auto-populate your Exchange server details. It connects to the latest version Exchange server in your organization by default. Review the detected settings:

• Exchange Server: Should show your CAS server
• Organization Name: Your Exchange organization identifier
• Version: Should display Exchange 2010, 2013, or 2016

If the auto-detection fails, manually specify your Exchange server FQDN:

Server FQDN: exchange01.contoso.local
Port: 443 (default for HTTPS)

Click Next to proceed to credential configuration.

The wizard requires administrative credentials for both your on-premises Exchange and Microsoft 365 environments to establish the hybrid connection.

On the Credentials page, configure the following:

On-premises credentials: The wizard will use your current Windows credentials by default. Ensure your account has:

• Exchange Organization Management permissions
• Local administrator rights on the Exchange server
• Domain administrator privileges

Exchange Online credentials: Enter your Microsoft 365 Global Administrator credentials:

Username: admin@contoso.onmicrosoft.com
Password: [Your secure password]

Click Next to validate both credential sets. The wizard will test connectivity to both environments.

This step configures the type of hybrid deployment. For quick migrations without ongoing integration, minimal hybrid is the optimal choice.

On the Hybrid Features page, select Minimal Hybrid Configuration. This option provides:

• One-time directory synchronization
• Mailbox migration capabilities
• Basic mail routing during migration
• No ongoing hybrid features (Free/Busy, etc.)

The wizard will display what features are included and excluded:

Included:
- Mailbox migration
- Directory sync (one-time)
- Basic mail routing

Excluded:
- Cross-premises Free/Busy
- ActiveSync redirection
- Secured mail flow
- Ongoing directory synchronization

Click Next to proceed to the configuration summary.

This step applies the hybrid configuration to your on-premises Exchange server, preparing it for mailbox migration to Microsoft 365.

On the Ready for Update page, review the configuration summary. The wizard will show all changes it will make to your environment:

• Create hybrid management objects
• Configure mail routing connectors
• Set up migration endpoints
• Prepare mailboxes for migration

Click Update to begin the configuration process. The wizard will display real-time progress:

Configuring hybrid deployment...
✓ Creating organization relationship
✓ Configuring send connectors
✓ Setting up migration endpoints
✓ Validating configuration

This process typically takes 10-20 minutes depending on your Exchange environment size and network connectivity.

After hybrid configuration, you need to sync your on-premises users to Microsoft 365. This is a one-time sync that won't continue running after migration.

On the User Provisioning page, select Synchronize my users and passwords one time. Click Download to get Microsoft Entra Connect (formerly Azure AD Connect).

Run the Entra Connect installer and select Express Settings:

# Express Settings Configuration
Directory to synchronize: [Auto-detected AD domain]
Azure AD sign-in: admin@contoso.onmicrosoft.com
Enterprise Admin: [Your domain admin account]
Password synchronization: Enabled

The sync process will start automatically. Monitor the progress in the Entra Connect interface:

Synchronization Status:
- Users discovered: 150
- Users synchronized: 150
- Errors: 0
- Sync duration: 5 minutes

After completion, directory sync automatically turns off, and users appear in the Microsoft 365 Admin Center.

Before migrating mailboxes, users need appropriate Microsoft 365 licenses. You can assign licenses individually or in bulk depending on your organization size.

In the Microsoft 365 Admin Center, go to Users > Active users. Select users who need Exchange Online licenses.

For bulk license assignment:

1. Select multiple users using checkboxes
2. Click Manage product licenses
3. Choose Assign licenses
4. Select appropriate license (e.g., Microsoft 365 Business Standard)
5. Configure Exchange Online settings

For PowerShell bulk assignment:

# Connect to Microsoft 365
Connect-MsolService

# Assign licenses to all unlicensed users
Get-MsolUser -UnlicensedUsersOnly | Set-MsolUserLicense -AddLicenses "contoso:EXCHANGESTANDARD"

# Verify license assignment
Get-MsolUser | Select DisplayName,Licenses

With users licensed and hybrid configured, you can now migrate mailboxes from on-premises Exchange to Exchange Online. Plan your migration in batches to minimize impact.

In the Microsoft 365 Admin Center, navigate to the Data migration page. Your synchronized users should appear in the migration list.

Create migration batches:

1. Select users for migration (start with 10-20 for testing)
2. Click Start migration
3. Choose migration options:

Migration settings:
- Batch name: Pilot_Batch_1
- Migration type: Remote move
- Target delivery domain: contoso.mail.onmicrosoft.com
- Bad item limit: 50
- Large item limit: 10

Monitor migration progress in real-time. Each mailbox shows status:

• Queued: Waiting to start
• In Progress: Data copying
• Completed: Successfully migrated
• Failed: Requires attention

After successfully migrating all mailboxes, update your DNS records to route mail directly to Microsoft 365 and complete the migration process.

In the Microsoft 365 Admin Center, go to Settings > Domains > select your domain > DNS records. Update the following records at your DNS provider:

MX Record (highest priority):

Priority: 0
Host: @ (or leave blank)
Points to: contoso-com.mail.protection.outlook.com
TTL: 3600

Additional required records:

# Autodiscover CNAME
Host: autodiscover
Points to: autodiscover.outlook.com
TTL: 3600

# SPF TXT Record
Host: @
Value: v=spf1 include:spf.protection.outlook.com -all
TTL: 3600

After DNS propagation (typically 1-4 hours), test mail flow by sending external emails to migrated users.

Decommission on-premises Exchange:

1. Verify all mailboxes migrated successfully
2. Confirm mail routing to Microsoft 365
3. Remove Exchange server from load balancer
4. Uninstall Exchange Server software