On February 19, 2025, Microsoft reiterated a pivotal announcement that has been on the radar of IT professionals for some time: Exchange Server 2016 and Exchange Server 2019 will reach the end of their support lifecycle on October 14, 2025. This decision marks the cessation of decades of reliance on these on-premises email and collaboration platforms, signaling a shift in how organizations must manage their communication infrastructure. With less than eight months remaining as of today, February 20, 2025, IT teams face a pressing need to prepare for this transition to avoid significant risks. Here’s what’s happening, how it could impact your organization, and the actionable steps to resolve it.
What Happened?
Microsoft’s support lifecycle for Exchange Server 2016 and 2019 is winding down, with the official end date set for October 14, 2025. After this point, the tech giant will no longer provide security patches, bug fixes, or technical support for these versions. This isn’t a sudden decision—Microsoft has been signaling this shift for years, encouraging users to modernize their environments. Exchange 2016, already in extended support since mainstream support ended in 2020, and Exchange 2019, which exited mainstream support in January 2024, have been soldiering on with critical updates. However, the clock stops ticking in October, leaving organizations still running these systems exposed unless they act.
The end of support aligns with a broader Microsoft strategy to push organizations toward cloud-based solutions like Exchange Online, part of Microsoft 365, while offering a subscription-based on-premises option, Exchange Server Subscription Edition (SE), expected in Q3 2025. This dual-path approach reflects the evolving landscape of enterprise IT, where flexibility and security are paramount, but it also places a tight timeline on IT teams to adapt.
The Potential Impact
The ramifications of sticking with Exchange 2016 or 2019 past the deadline are far-reaching and could hit organizations hard if ignored. Here’s how it could play out:
- Security Vulnerabilities: Without security patches, these servers will become prime targets for cybercriminals. Unpatched systems are a known weak point—think of past Exchange exploits like ProxyLogon in 2021, which compromised thousands of organizations. Post-October 2025, any new vulnerabilities discovered won’t be fixed, amplifying the risk of breaches.
- Compliance Risks: Regulations like GDPR, HIPAA, and others mandate the use of secure, supported software. Running outdated Exchange versions could lead to audits, fines, or legal headaches if a security incident occurs and unsupported software is implicated.
- Operational Disruptions: No more bug fixes or technical support means IT teams will be on their own to troubleshoot issues. A critical failure could result in prolonged email downtime, stalling communication and productivity—a nightmare for any business.
- Rising Costs: Maintaining legacy systems without vendor support often requires custom workarounds or third-party assistance, driving up operational expenses. Older software also lacks modern features, slowing down workflows and frustrating users.
The impact isn’t just technical—it’s strategic. Organizations delaying action risk falling behind competitors who leverage modern, cloud-enabled tools for efficiency and scalability. With related products like Office 2016, Office 2019, and Skype for Business also losing support on the same date, the stakes are even higher for those with interconnected Microsoft ecosystems.
How to Resolve It
The good news? There’s still time to act, and Microsoft has outlined clear paths forward. Here’s what IT teams must do now to navigate this transition:
- Assess Your Environment
Start by auditing your current setup. Are you running Exchange 2016, 2019, or a hybrid configuration? How many mailboxes, servers, and dependencies (like Outlook or Skype) are involved? Understanding your scope is the first step to a smooth migration. - Choose Your Path: Cloud or On-Premises
- Option 1: Migrate to Exchange Online
Microsoft’s preferred solution is Exchange Online, available standalone or via Microsoft 365. This cloud platform offers continuous updates, built-in security, and scalability, eliminating end-of-support worries. Use tools like the Exchange Deployment Assistant and Microsoft’s migration guides to plan the shift. For hybrid setups, ensure your management server is upgraded (more on that below). - Option 2: Upgrade to Exchange Server SE
For those committed to on-premises infrastructure, Exchange Server Subscription Edition (SE) launches in Q3 2025—just before the deadline. It’s subscription-based, requires Software Assurance, and promises modern features like TLS 1.3. If you’re on Exchange 2019, an in-place upgrade to SE is possible. From Exchange 2016, you’ll need to first upgrade to 2019 (no in-place option exists), then to SE, involving new hardware and mailbox migrations.
- Option 1: Migrate to Exchange Online
- Plan and Test the Migration
Time is tight, especially for complex environments. For Exchange Online, start migrating mailboxes in batches, testing connectivity and user experience. For SE, deploy Exchange 2019 now if you’re on 2016, then prepare for the SE upgrade. Test in a staging environment to avoid surprises—downtime isn’t an option. - Update Related Systems
With Office 2016/2019 and Skype for Business also retiring, ensure clients and integrations (like Outlook) are upgraded to supported versions (e.g., Microsoft 365 Apps). This prevents compatibility issues post-migration. - Enhance Security Now
Apply the latest cumulative updates (e.g., Exchange 2019 CU15, due soon) and security patches to stay protected until you transition. Enable MFA, review firewall rules, and monitor for suspicious activity to bridge the gap. - Communicate with Stakeholders
Inform leadership and users about the timeline, potential disruptions, and benefits of the upgrade (e.g., improved security, new features). Buy-in and training will ease the shift.
Why This Matters Now
Eight months might sound like plenty of time, but migrations—especially for large organizations—can take months of planning, testing, and execution. Exchange Server SE’s Q3 2025 release cuts it close to the October deadline, leaving little room for error if delays occur. Meanwhile, cybercriminals won’t wait—unpatched systems could be exploited well before support ends if IT teams drag their feet.
This isn’t just about avoiding risk; it’s about future-proofing. Exchange Online offers AI-driven tools and seamless integration with Microsoft 365, while SE keeps on-premises fans in the game with modern capabilities. Acting now positions your organization to thrive, not just survive.
Final Thoughts
Microsoft’s end of support for Exchange 2016 and 2019 isn’t a surprise, but it’s a deadline IT teams can’t afford to miss. Whether you go cloud with Exchange Online or stay on-premises with Exchange Server SE, the time to plan is now. Assess, decide, and move—because October 14, 2025, will be here before you know it. Don’t let your email system become a liability; turn it into an asset for the future.