Step 1: Plan Your Migration
Assess Your Current Environment
- Identify your Exchange Server version (Exchange 2010, 2013, 2016, 2019).
- Determine the number of mailboxes, distribution lists, and public folders.
- Ensure Active Directory is healthy and up to date.
- Verify bandwidth requirements for data migration.
Choose a Migration Strategy
There are three main migration types:
- Cutover Migration (For fewer than 2,000 mailboxes, Exchange 2013 and below)
- Staged Migration (For Exchange 2003/2007 with more than 150 mailboxes)
- Hybrid Migration (For Exchange 2010 and later, allows coexistence)
Step 2: Prepare for Migration
1. Verify Domain Ownership in Microsoft 365
- Sign in to Microsoft 365 Admin Center.
- Navigate to Settings > Domains and add your domain.
- Verify the domain using TXT/MX records provided by Microsoft.
2. Set Up Directory Synchronization (If Required)
- If using Hybrid or Staged Migration, install Azure AD Connect to sync on-prem AD to Azure AD.
- Configure password hash synchronization or federation for seamless login.
3. Assign Licenses in Office 365
- Ensure all users have a valid Microsoft 365 license (Exchange Online Plan).
Step 3: Perform the Migration
1. Cutover Migration (For Small Deployments, Exchange 2013 & Below)
- In Exchange Admin Center, navigate to Recipients > Migration.
- Select New Migration Batch > Cutover Migration.
- Add users to migrate and start the batch.
- Once complete, switch the MX record to Office 365.
2. Staged Migration (For Exchange 2003/2007 with Many Users)
- Create a CSV file with mailbox details.
- In Exchange Admin Center, go to Recipients > Migration.
- Select New Migration Batch > Staged Migration.
- After migration, change MX records and complete the cutover.
3. Hybrid Migration (For Coexistence, Exchange 2010 and Later)
- Run Hybrid Configuration Wizard (HCW) from Exchange Admin Center.
- Configure mail flow (Exchange Online Protection).
- Migrate batches of mailboxes gradually.
Step 4: Post-Migration Tasks
1. Update DNS Records
- Change MX records, Autodiscover, SPF, DKIM, and DMARC to point to Office 365.
2. Verify Mail Flow and Client Connectivity
- Ensure Outlook and mobile devices are connecting correctly.
- Test email sending/receiving from external domains.
3. Decommission Old Exchange Server
- Once all mailboxes are migrated, remove the old Exchange server.
- Uninstall Azure AD Connect if not required anymore.
4. Train Users and Provide Support
- Educate users about Office 365 features.
- Set up OneDrive and Teams for collaboration.
Step 5: Monitor and Optimize
- Use Microsoft 365 Admin Center and Exchange Online PowerShell to monitor mail flow.
- Set up compliance policies, retention rules, and security measures.
- Regularly update licenses and manage storage quotas.