Microsoft Exchange Server 2016 and 2019 are approaching a critical milestone, with both versions reaching their end of extended support on October 14, 2025.
While existing installations will continue to function after this date, Microsoft has emphasized the importance of planning ahead, stating “Customer installations of Exchange 2016 and Exchange 2019 will of course continue to run after October 14, 2025; however, due to the upcoming end of support date and potential future security risks, we strongly recommend customers act now.”
For Exchange 2019 users, Microsoft recommends keeping systems updated and preparing for the upcoming Exchange Server Subscription Edition. Exchange 2016 users are advised to first upgrade to Exchange 2019 and then prepare for the SE migration. This staged approach is particularly important considering the limited timeframe – there will be less than four months between the release of Exchange Server SE in early Q3 2025 and the October 14, 2025 end-of-support deadline.
Impact on Organizations
After the support deadline, users will face several critical limitations:
- No technical support for emerging problems
- No bug fixes for stability and usability issues
- No security patches for newly discovered vulnerabilities
- No time zone updates
Migration Options
Exchange Server Subscription Edition
Organizations preferring to maintain on-premises infrastructure can prepare for the upcoming Exchange Server Subscription Edition (SE). Key details about SE include:
- Code equivalent to Exchange 2019 CU15
- Available for download through the Microsoft 365 admin center
- Requires subscription licenses or active Software Assurance for both server and Client Access Licenses (CALs)
- Initial release in early Q3 2025, with CU1 following in late 2025
Exchange Online Migration
Organizations can choose to migrate their email infrastructure to Exchange Online or Microsoft 365, which provides cloud-based email and collaboration services.
Recommended Actions
For Exchange 2019 Users
- Ensure you’re running CU14 or CU15 to enable in-place upgrade to SE
- Keep servers updated with the latest cumulative updates
- Prepare for SE migration when available
For Exchange 2016 Users
- Upgrade to Exchange 2019 immediately
- Decommission Exchange 2016 servers
- Ensure upgrade to CU14 or CU15 when available
- Prepare for SE migration
What Happens When a Product Reaches End of Support?
End of support marks a critical transition point where organizations face increased risks and challenges. Organizations continuing to use unsupported products may experience:
- Security Vulnerabilities: Systems become increasingly vulnerable to security breaches without ongoing security patches and updates.
- Stability Issues: Without bug fixes and technical support, system stability and reliability may deteriorate over time.
- Compliance Risks: Running unsupported software can lead to compliance violations in regulated industries.
- Productivity Impact: Unresolved technical issues and compatibility problems can reduce workplace efficiency.
Important Timeline Details
Critical Dates
- Exchange 2019 CU15 release: Early 2025
- Exchange Server SE release: Early Q3 2025 (July-August timeframe)
- Exchange Server SE CU1: Late 2025
- End of support deadline: October 14, 2025
Legacy Systems
- Exchange Server 2013 is already out of support (since April 11, 2023)
- All legacy systems must be removed before installing Exchange Server 2019 CU15 or upgrading to Exchange Server SE
- The migration window between SE release and end of support is approximately 3 months
Additional Considerations
Organizations should note that several related Microsoft products will also reach end of support on October 14, 2025, including:
- Microsoft Office 2016 and 2019
- Outlook 2016 and 2019
- Skype for Business 2016 and 2019
- Windows 10
While servers will continue operating after the end-of-support date, organizations should act promptly to ensure their email infrastructure remains secure and supported.
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