Countdown to Shutdown: Exchange Server 2016 & 2019 Support Ends in October 2025

If your organization is still running Exchange Server 2016 or 2019, it’s time to mark your calendar—and more importantly, start planning. On October 14, 2025, Microsoft will officially end support for both versions, bringing a critical chapter of on-premises email infrastructure to a close.

🛑 What’s Happening?

As of that date:

• No more Cumulative Updates (CUs)
• No security patches
• No support from Microsoft—even for critical vulnerabilities

While Exchange Server 2019 was originally expected to have a longer lifecycle, Microsoft has synchronized its end-of-support (EOS) with Office 2016/2019 and Windows 10 to help organizations plan cohesive migrations across platforms.

⚠️ Why This Matters

Running an unpatched Exchange environment is more than just outdated—it’s dangerous.

Recent years have shown us what happens when attackers exploit unprotected Exchange servers. High-profile threats like:

• ProxyLogon
• Hafnium
• and other zero-days

have led to widespread data breaches, ransomware infections, and compliance nightmares.

After October 2025, if new vulnerabilities are discovered, Microsoft won’t fix them. That means every Exchange 2016/2019 server becomes a potential attack surface.

🧭 What Are Your Options?

Microsoft recommends two main paths forward:

☁️ 1. Exchange Online (Microsoft 365 Cloud)

• Fully managed and regularly patched by Microsoft
• Seamless integration with Teams, OneDrive, and SharePoint
• Reduced infrastructure and operational overhead

This is the preferred route for most organizations aiming for agility, scalability, and long-term security.

🖥️ 2. Future Exchange Server Subscription Edition

• Designed for hybrid/on-prem environments
• Will require subscription licensing
• Available only to customers in active Software Assurance or equivalent agreements

If you're in a highly regulated industry or must retain on-prem mailboxes, this is your path—but you’ll still need to migrate from Exchange 2016/2019 to this future version.

🧮 What You Should Do Now

• Audit your Exchange servers—identify version, patch level, and usage
• Evaluate your migration strategy—Cloud-first? Hybrid?
• Plan your timeline—Don’t wait until Q3 2025 to act
• Inform stakeholders—Compliance, security, and IT ops all need to be aligned
• Explore Microsoft FastTrack or certified migration partners