Migration from Exchange 2016 to Exchange Server 2019 – 2,700 mailboxes

We were tasked with migrating the customer’s Exchange 2016 to Exchange 2019. The Exchange 2016 environment was deployed on Windows Server Windows Server 2012 R2, which was reaching the end of support. The Exchange hybrid mode was configured. The end-users were mostly using Outlook 2013 for Windows, various ActiveSync devices, and OWA.

• The new Exchange 2019 environment (the latest Cumulative Update and security updates) was built on Windows Server 2022, deployed and configured in two geographically distant data centers to ensure high availability and site resilience.
• The Autodiscover SCP, virtual directories, and certificates were configured on the new servers.
• New IP-less DAG and mailbox databases were created with 4 copies each.
• The Client Access Services, both internal and external, were migrated to new F5 VIPs, which allowed extensive testing to be performed before putting the system into production.
• The email flow was simplified, and dedicated receive connectors were configured for emails coming from the message hygiene system, internal applications, and scanning devices (emails relayed through Exchange), and Microsoft 365.
• The mailboxes and public folders were migrated to Exchange 2019, taking into account their size and number to ensure balanced mailbox databases.
• The dependent systems were configured and tested (e.g., the Identity Management application, SCOM backup, the room booking system, and the antivirus software, including the necessary exclusions).
• Finally, the Exchange 2016 infrastructure was decommissioned.

The customer was migrated to Exchange 2019 with the latest cumulative update and security updates on Windows Server 2022 machines that will be supported for many years. The migration process was completely transparent to the end users.