Exchange Server 2016/2019 end of life – all you need to know

Exchange 2016/2019 end of life (EOL) date was October 14, 2025. It’s high time to plan how you want to handle the unsupported – and, as a result, insecure – versions – and where to go from here.

A few words about Exchange Server lifecycle

If you’ve never heard about terms like mainstream support vs extended support or Exchange support matrix, I’ll dish out some basics.

Exchange support matrix aka Exchange Server supportability matrix provides information on the supported Exchange Server versions together with underlying Windows Servers they should be deployed on and which email clients are officially supported. You can find the matrix here.

In short, there are three standard support phases in Exchange Server 2016 & 2019 lifecycle (like with any other Microsoft Exchange Server that follows the Fixed Lifecycle Policy) + two additional:

• Mainstream Support – this is when your server is fully supported, so it receives regular bug fixes, security updates (SU) and new features with cumulative updates (CU). That said, we’ve seen that the “new features” part has been mainly the domain of Exchange Online for some time now. Anyway, during the mainstream support, you, as the Exchange Server admin, can request changes and new features, report bugs that you’ve identified, as well as contact Microsoft’s support team. This period lasts 5 years after the release of a given Exchange Server version. For Exchange 2016 and 2019, it’s history now.
• Extended Support – in this next period, you can count only on the security patching. Quarterly Cumulative Updates (CU) become history, just like any hopes for new features. Both Exchange Server 2016 and Exchange Server 2019 are beyond this phase now.
• Beyond the End of Support – it’s called end of life for a reason. This is when Microsoft no longer supports a given Exchange version. With no more security updates on the horizon (unless a critical vulnerability is identified), continuing the use of such a version introduces constant risks. In case of any problems, you need to resort to using your own “street-smarts” or cry for other admins’ help. The volume of threads on various tech communities (and, not to brag, the comment section on some of my articles) is living proof that maintaining a secure server after its end of life is increasingly difficult. Exchange 2016 & Exchange 2019 entered this phase on October 14, 2025.
• Extended Security Update (ESU) program – this was an optional program that offered Security Updates after the official end of life. For Exchange Server 2016 and 2019, it started in October 2025 and ended on April 14, 2026. While the ESU program provided Critical and Important updates only and was not free of charge, the Security Updates released in December 2025 and February 2026 quickly proved its value to all who enrolled.
• Period 2 Exchange Extended Security Update (ESU) program – if you thought the ESU program was the final chapter of the Exchange 2016 & 2019 story, here’s yet another plot twist – on April 15, 2026, Microsoft announced a Period 2 Exchange ESU program, running from the start of May 2026 (with purchases available starting April 15) through the end of October 2026. During this period, Critical and Important updates will be released in the same way as during Period 1. Note that Period 2 is not an automatic extension of the original ESU phase – to benefit from Period 2 SUs, you must re-enroll (and pay a separate fee).

Why is the end of life different this time?

Every time an Exchange Server reaches its end of life, it’s an important event for sysadmins all over the world. I’ve already mentioned that, in theory, you can keep using an unsupported Exchange environment. But in case of any problems, you’re basically on your own. This time, there are a few twists to keep in mind:

1. Both Exchange 2016 and Exchange 2019 reach end of life at the same time. Personally, I’ve always thought of Exchange 2019 as a 2016 in disguise, but cutting its lifespan by nearly 3 years was a kind of surprise for me. After October 14, 2025, Exchange Server Subscription Edition is the only on-premises Exchange Server to be supported. More on the subject of migration in a moment.
2. This time, the end of Extended Support is even more important for all hybrid organizations out there. Since Microsoft introduced Transport Enforcement System in Exchange Online, keeping your on-premises environment up to date is vital. If you’re behind on the updates, your environment is treated as “persistently vulnerable” and mail flow from such servers will first be throttled and then blocked. The policy has been recently deployed for Exchange 2016 and 2019. Read more about Transport Enforcement System in Exchange Online and how to prevent your emails from being blocked

What are your Exchange Server upgrade or migration options?

Email is one of the crucial company assets that holds precious and confidential business information. That’s why you shouldn’t ignore the news about the Exchange Server end of life. If you haven’t made any plans concerning this date, remember that your Exchange 2016 or 2019 environment is already in an unsupported state. You should start planning your upgrade or migration route now to make sure your company data stays safe. There are two most obvious escape routes:

• Upgrade to Microsoft Exchange Server Subscription Edition (vNext)
• Migrate from Exchange Server to Microsoft 365 (Office 365)

Upgrade to Microsoft Exchange Server Subscription Edition (vNext)

If you want to continue using on-premises infrastructure provided by Microsoft, Exchange Server Subscription Edition (SE) is the only available upgrade path. Let’s quickly browse through its pros and cons:

• A familiar solution.
• Full control over data stored locally (security and compliance-related reasons).
• No fixed date for end of life – Exchange Server Subscription Edition has been advertised as the last Exchange Server version which you’ll get support for, as long as you’re a subscriber. If it comes to an end, after all, you’ll get a heads-up at least 12 months before the support ends.
• An easy in-place upgrade from Exchange Server 2019 CU15 (that’s new for on-premises Exchange migration).
• Change of pricing policy – it’s no longer a one-off payment but an ongoing commitment.
• Necessity to upgrade scripts (switch to the Admin API that uses Exchange Online cmdlets).
• No coexistence with previous Exchange Server distributions.

Learn more about Exchange Server Subscription Edition (SE)

Now the question is – what if you have an older environment, like Exchange 2010 or 2013, and want to migrate straight to Exchange Server Subscription Edition? Since coexistence with these Exchange Servers is not possible, you need to perform a “traditional” native double-hop migration (Exchange 2010 > Exchange 2016, then decommission Exchange 2010 and migrate from Exchange 2016 to Exchange SE). There’s also an easier way – you can use CodeTwo Exchange Migration to make the transition smooth, easy, and reliable.

Migrate from Exchange Server to Microsoft 365 (Office 365)

This path is for those who have postponed their migration to the cloud, but don’t have their hands tied by policies and compliance reasons. Now that one of the reasons for staying on-premises no longer applies due to the licensing model change, the decision might be easier.

Here’re the pros and cons of going 100% cloud:

• Access to the latest features from Microsoft.
• Updates, including security updates, done automatically by Microsoft.
• Lower costs of infrastructure maintenance.
• Less complex environment.
• Highly secure Microsoft servers in Azure.
• Company data stored externally, beyond company control (which can be remediated with a reliable backup solution).
• Dependency on Microsoft infrastructure health and support team.
• Subscription pricing model requires an ongoing commitment (it’s the same for Exchange Server SE, though).
• Full-scale migration required – either with the native, scripting-intensive methods or through third-party solution like CodeTwo Office 365 Migration that uses easy Next-Next-Finish wizards.