A Quick Guide on How to Navigate Exchange Server’s Final Evolution

For more than 20 years, Microsoft’s on-premises Exchange Server solutions have played a pivotal role in the world of collaborative technology. Traditionally, Microsoft has offered a steady support framework for Exchange Server with major feature updates occurring every three to four years while providing extended support for the preceding two versions. This ensured the delivery of bug fixes and security patches to those using older versions while continuing to improve the overall solution.

Yet, this two-decade-old practice will soon evolve. Both Exchange 2016 and 2019 are scheduled to reach their end of extended support on Oct. 14, 2025, which means they will thereafter no longer receive updates for bugs or security issues. This article outlines the implications of the end-of-life status for on-premises Exchange users and the pathways available to maintain ongoing support and security.

Exchange Server Subscription Edition (SE) is the next version of Exchange Server for on-premises deployments. Exchange Server SE is a subscription-based product that will initially offer the same features and functionality as Exchange Server 2019, but with a different licensing and servicing model.

Exchange Server SE will require subscription licenses or licenses with active Microsoft Software Assurance (SA) for both server and user licenses. Updates will come via standard cumulative updates delivered twice yearly, with the first one expected in the second half of 2025. These will include feature updates as well as security and bug fixes.

Customers will need to keep their servers current to remain supported. Unlike in the past, when you could linger on an older version of Exchange Server and keep applying security patches, now your organization will need to adapt to features as they are pushed to the only supported version of Exchange Server.

For customers who are leveraging the free hybrid server licenses for integration with Exchange Online, that will continue to be an option in Exchange Server SE, assuming you meet the following requirements:

• You have an existing, non-trial Office 365 subscription
• You do not have another licensed Exchange Server in the environment
• You are not hosting any mailboxes on the hybrid Exchange Server

It is recommended that that these servers be upgraded to Exchange Server SE for environments that are currently using, or are planning to use, Exchange hybrid servers as a part of their long-term Exchange architecture.

Customers who have mailboxes hosted on any version of Exchange Server on-premises have the following high-level options for those mailboxes:

1. Migrate to Exchange Online

2. Upgrade or migrate to Exchange Server SE when it becomes available in the second half of 2025

3. Serverless management with Exchange Online

Depending on your current state and your desired future state, this may be a multi-step process. For example, to maintain support, you may need to complete an upgrade to Exchange Server SE while you are completing or planning a migration to Exchange Online. The situations outlined below are intended to be informative but are not the best path for every organization. Please engage with your CDW account team to learn more about these options.

Option 1: Migrate to Exchange Online

Exchange Online has come a long way since its launch in 2011. In addition to no longer needing to worry about end-of-life issues, server patching, storage and resiliency, Exchange Online is getting feature updates much more regularly than the on-premises service. Even for organizations who are not planning to take advantage of the full Microsoft 365 suite, a transition to just Exchange Online is a viable, if not particularly common, option for customers.

A migration to Exchange Online will frequently require a currently supported version of Exchange to be set up as a hybrid server to facilitate the transition to Exchange Online. So, if you are working on a version of Exchange 2013 or older, you will likely get an updated version of Exchange installed in your environment to aid in that transition. For customers who elect to retain an Exchange Hybrid Server to support management tools and SMTP relay, this server should be upgraded to Exchange Server SE as well, even if it’s not hosting any mailboxes.

Option 2: Upgrade to Exchange Server SE

For customers planning to keep their email servers in their own data center, Exchange Server SE is the obvious next step. The initial update might not have many new features to excite users, but it’s expected to introduce what’s needed to support the upcoming servicing model. Major updates shouldn’t be anticipated until Microsoft begins to deliver cumulative updates for SE in October 2025. For customers already on Exchange Server 2019 and Windows Server 2022, only a CU update is required.

For customers who are on Exchange Server 2016 or older, you will need to start developing a plan to complete migration to Exchange SE. Exchange Server SE will not support coexistence with any unsupported versions of Exchange, which means customers will need to upgrade all their Exchange Servers if they plan to remain on premises.

Option 3: Serverless Management With Exchange Online

Starting with Exchange 2019 CU 12, it has been possible to decommission your final Exchange Server and perform your Exchange Recipient Management tasks via PowerShell. While there is no Exchange license cost in maintaining an Exchange Hybrid Server, many organizations want to do away with the Windows Server costs and corresponding maintenance. According to Microsoft, for those customers, this could be a viable option if all the following statements are true for your organization:

• You migrated all mailboxes and public folders to Exchange Online (no on-premises Exchange recipients)
• You do not use SMTP Relay capabilities of the Exchange Hybrid Server
• You use AD for recipient management and cloud sync or Microsoft Entra Connect for synchronization
• You do not use or require the on-premises Exchange admin center or Exchange role-based access control (RBAC)
• You are comfortable using only Windows PowerShell for recipient management
• You do not require auditing or logging of recipient management activity
• You are running only one on-premises Exchange Server and only for recipient management
• You want to manage recipients without running any Exchange Servers

For organizations planning to stay in the Microsoft ecosystem with Exchange Servers on premises, there is no reason to not start planning and transitioning to Exchange Server 2019 and Windows Server 2022. While Exchange Server 2019 CU 15 is not available today, being able to perform an in-place CU upgrade to your server is a whole lot better than needing to plan and execute a cross-version Exchange Server migration.

For Exchange Online customers who only have an Exchange Hybrid Server in place, now is a good time to consider whether you need to keep your Exchange Server around or if you could operate without it.

CDW has extensive experience supporting our customers’ Exchange environments — supporting over 200 Exchange customers in 2023 alone. Whether you’d like to remain on premises, move to Exchange Online, move to a third-party or something in between, CDW can help. We can review your current environment and help you develop a plan to ensure you can meet the deadlines and remain supported. October 2025 is coming up quickly, so now is the time to start planning to get your environment ready for this major shift for Exchange Server.