Migrating mailboxes from an on-premises Exchange Server to Office 365 (Microsoft 365) involves several steps to ensure a smooth transition. Here's a general guide outlining the process: Preparing for Migration Review System Requirements: Ensure your current Exchange Server version is compatible with the migration tools and meets Office 365 system requirements. Verify Domain Ownership: Confirm that you own the domain you want to use with Office 365. License and Subscription: Acquire the necessary Office 365 licenses and subscriptions for your organization. Network Readiness: Ensure network connectivity and bandwidth are sufficient for data migration. Steps for Migration 1. Assessing Current Environment Identify Mailboxes: Determine which mailboxes need to be migrated and prioritize them based on business needs. Inventory and Permissions: Create an inventory of mailboxes, their sizes, and any special permissions or configurations. 2. Choose Migration Method There are several migration methods depending on your current Exchange Server version and your preferences: Cutover Migration: Suitable for smaller organizations with fewer than 1000 mailboxes. It involves migrating all mailboxes at once. Staged Migration: Involves migrating mailboxes in batches. Hybrid Deployment: Ideal for larger organizations that want to maintain both on-premises Exchange and Office 365 mailboxes simultaneously. IMAP Migration: Can be used for non-Exchange email systems. 3. Prepare Office 365 Set Up Office 365 Tenant: Create accounts and set up DNS records. 4. Perform the Migration Use Migration Tools: Microsoft provides tools like the Exchange Admin Center (EAC) or PowerShell commands for migrations. Start Migration Batches: Initiate migration batches based on the chosen method. 5. Verify and Monitor Monitor Migration Progress: Keep an eye on the migration progress using logs or monitoring tools. Test Mailbox Access: Verify that users can access their mailboxes on Office 365. 6. Complete the Migration Finalize Migration: Complete any final steps required by your chosen migration method. Update DNS Records: Point your domain's MX (Mail Exchange) records to Office 365. Post-Migration Tasks User Training: Provide training to users on using Office 365 features and accessing their new mailboxes. Configuration and Testing: Configure additional Office 365 features (e.g., SharePoint, OneDrive) and perform testing. ** Decommission On-Premises Exchange**: Once all mailboxes are successfully migrated, decommission your on-premises Exchange Server (if desired). Tools and Resources Exchange Admin Center (EAC): Access migration tools and perform mailbox moves. Microsoft 365 Migration Advisor: Provides recommendations and guidance for mailbox migrations. PowerShell Scripts: Useful for automating migration tasks and monitoring. Considerations and Best Practices Backup: Always have a backup of your data before starting the migration. Communication: Keep users informed about the migration schedule and any changes. Security and Compliance: Ensure security measures and compliance requirements are met during and after migration. By following these steps and best practices, you can successfully migrate your Exchange Server mailboxes to Office 365 with minimal disruption to your organization's operations. Related articles: EDB to PST Converter | Recover Deleted Exchange Mailbox | EDB Recovery tool | Export Exchange Public folder to PST | Shoviv Exchange Server Suite | Migrate Exchange 2013 to Office 365 | Migrate into Office 365 from Exchange 2016 | Office 365 to Office 365 Migration | Exchange to Office 365 | Office 365 to pst | Extract EDB to PST |