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Exchange Server SE Upgrade Guide: Moving from Exchange 2016 and 2019

Exchange Server Subscription Edition (SE) is Microsoft’s current on premises version of Exchange, released on July 1, 2025, to replace Exchange Server 2016 and 2019, which reached end of support on October 14, 2025. Organizations on Exchange 2019 CU14 or CU15 can upgrade to Exchange SE in place, like installing a cumulative update. Organizations on Exchange 2016 need new servers and mailbox moves. Exchange SE also requires subscription licensing rather than perpetual licenses.

This guide explains the upgrade paths, licensing and planning steps. RockTeam delivers Exchange upgrades as part of our Microsoft Exchange consulting and support services.

What Exchange Server SE Is

The first release of Exchange SE uses the same code as Exchange 2019 CU15 with security updates, under a new name and version. Later updates bring changes such as Kerberos for server to server communication, removal of Outlook Anywhere (RPC over HTTP) and new REST-based administration APIs, with updates expected twice a year.

Exchange SE Upgrade Paths

Current versionPath to Exchange SEWhat it involves
Exchange 2019 CU14 or CU15In-place upgradeInstall Exchange SE like a cumulative update on each server
Exchange 2019 earlier CUUpdate firstMove to CU14 or CU15, then upgrade in place
Exchange 2016Legacy upgradeBuild new Exchange SE or 2019 CU15 servers, move mailboxes and services, then remove 2016
Exchange 2013 or earlierMulti-step or migrateCannot coexist with Exchange 2019 or SE; move through an intermediate version or migrate to Exchange Online

Licensing Changes

Exchange Server SE requires subscription licenses or licenses covered by active Software Assurance. Perpetual Exchange Server licenses and CALs for 2019 and earlier without Software Assurance do not cover SE. Review your agreements before planning the upgrade; see our software licensing and renewals services.

Exchange SE Upgrade Checklist

  1. Inventory servers, versions, CUs, roles, databases and DAGs.
  2. Confirm licensing covers Exchange SE.
  3. Check prerequisites: supported Windows Server versions, .NET and other dependencies.
  4. Review dependencies: Outlook clients still using Outlook Anywhere, third-party archiving, backup, anti-spam and applications that relay mail.
  5. Back up and confirm you can restore.
  6. Upgrade in a test environment or a single server first.
  7. Upgrade remaining servers one at a time, keeping DAGs and load balancing healthy.
  8. Apply security updates and confirm hybrid, mail flow and clients work.

Exchange SE or Exchange Online?

Stay on Exchange Server SE whenMove to Exchange Online when
Data must stay on infrastructure you controlYou want Microsoft to run the servers and updates
Applications depend on on premises ExchangeYou are already moving to Microsoft 365
You run hybrid and keep a server for recipient managementYou want to retire on premises servers
Network or regulatory constraints limit cloud useMailbox growth and maintenance are a burden

If you are moving, see our guide to Exchange to Office 365 migration.

Still running Exchange 2016 or 2019?

RockTeam’s Exchange consultants plan and deliver upgrades to Exchange Server SE, or migrations to Exchange Online, with tested runbooks and rollback plans. Start with a no cost assessment.

Explore Exchange Consulting

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Exchange Server SE FAQs

Exchange Server SE is Microsoft’s current on premises Exchange Server, released July 1, 2025, replacing Exchange 2016 and 2019 and licensed by subscription.

October 14, 2025.

Yes, from Exchange 2019 CU14 or CU15. Install Exchange SE on each server like a cumulative update.

Build new servers running Exchange SE or Exchange 2019 CU15, move mailboxes and services to them, then decommission the Exchange 2016 servers.

Exchange SE requires subscription licenses or licenses with active Software Assurance. Perpetual licenses without Software Assurance do not cover it.