Exchange 2016 CU23 SU22 EOL Oct 2025: 3 Options

The End-of-Life Deadline for Exchange 2016 CU23 SU22

Microsoft Exchange 2016 Cumulative Update 23 with Security Update 22 (version 15.1.2507.69) will reach end of life on October 14, 2025. That is roughly nine months from today. This release is not an LTS (Long-Term Servicing Channel) release, meaning it never qualified for extended support beyond the standard lifecycle. Active support ended on October 13, 2020.

After October 14, Microsoft will no longer provide security patches, bug fixes, or technical support for this build. If your organization still runs Exchange 2016 CU23 SU22, you have three realistic paths forward. Nine months is sufficient time to execute any of them, but each option carries distinct trade-offs in cost, risk, and operational fit.

Option 1: Migrate or Upgrade to a Supported Exchange Version

The first—and most conventional—path is to migrate to a currently supported version of Exchange, or to Exchange Online as part of Microsoft 365.

Cost Profile

• Licensing: New Exchange Server licenses (if on-premises) or subscription costs for Exchange Online. These can be substantial, especially if you must also upgrade underlying Windows Server or Active Directory.
• Migration labor: Internal IT time or external consulting fees to plan, test, and execute the migration. For complex environments (multiple sites, custom apps, large mailboxes), this is often the largest cost.

Risk

• Low to moderate if the migration is well-planned and tested. The biggest risk is unexpected incompatibility with line-of-business applications that depend on Exchange Web Services or on-premises directory integration.
• Moderate if you move to Exchange Online: you must manage data sovereignty, compliance, and network bandwidth for mail flow.

Timeline

• 6–9 months for a typical migration, assuming you start now. Simpler environments can do it in 3 months; heavily customized ones may need 12 months.

Best For

• Organizations that are already planning a broader digital transformation or hybrid cloud strategy.
• Environments where the Exchange workload is under active development or where new features are needed.

Option 2: Purchase Vendor Extended Support (If Offered)

Microsoft historically offers Extended Security Updates (ESU) for Exchange Server after end of life, but only for certain versions and only for a limited period. As of this writing, Microsoft has not announced ESU for Exchange 2016 CU23 SU22. You should verify directly with your Microsoft account team.

Cost Profile

• High per-server cost if available. ESUs are priced per virtual machine or physical server per year, and the price typically doubles in the second year.
• No new features or non-security fixes. You pay only for critical security patches.

Risk

• Low for security coverage, but you remain on an unsupported platform. No bug fixes for performance or reliability issues.
• High if ESU is not offered at all—then this path is unavailable.

Timeline

• Requires immediate action. ESU enrollment windows are usually short and come with sign-up deadlines months before end of life.

Best For

• Organizations that need a temporary bridge (1–2 years) while planning a migration, and for whom the cost of ESU is acceptable.

Option 3: Switch to Third-Party Support

Third-party maintenance providers like 3rd Party Support can continue to deliver security patches, bug fixes, and technical support for Exchange 2016 CU23 SU22 after Microsoft’s end-of-life date.

Cost Profile

• Typically 50–70% less than the combined cost of new licenses plus Microsoft’s ESU (if offered). Pricing is per-server subscription, predictable, and often negotiable for multi-year contracts.
• No licensing upgrade required. You keep your existing Exchange infrastructure.

Risk

• Low for environments that are stable and not changing. Third-party support does not provide new features, but it does provide custom patches for CVEs and operational issues.
• Moderate if your organization requires Microsoft’s own patches for compliance or insurance reasons. Some auditors may require a written exemption letter.

Timeline

• Can be implemented in 2–4 weeks. No migration, no downtime. Contract signing and onboarding are straightforward.

Best For

• Stable, mature Exchange deployments where the primary need is to keep mail flowing securely and reliably.
• Budget-conscious organizations that want to defer capital expenditure for a migration.
• Environments where the risk of ESU not being offered is unacceptable.

Decision Checklist

Use this quick checklist to decide which path fits your environment.

Criterion	Go with Migration	Consider Extended Support	Go with Third-Party Support
Need new features	✅ Yes	❌ No	❌ No
Cloud/ hybrid strategy in play	✅ Yes	❌ Not planned	❌ Not planned
Budget available for new licenses	✅ High	❌ Moderate	❌ Low
Compliance requires vendor-backed patches	✅ Yes	✅ Yes	⚠️ Verify with auditor
Time to execute	6–9 months	Weeks (if offered)	2–4 weeks
Best for stable workloads	❌ Overkill	⚠️ Temporary	✅ Ideal

Next Steps

Whatever path you choose, start the assessment now. Nine months is enough time, but only if you act deliberately.

• If you plan to migrate: Begin discovery and planning this month. Create a sandbox test environment.
• If you want extended support: Contact your Microsoft account executive immediately to confirm availability and pricing.
• If you prefer third-party support: Contact our team to discuss a support contract for Exchange 2016 CU23 SU22. We can usually onboard in under 30 days.

For documentation on the lifecycle, refer to the Microsoft Exchange lifecycle page or our Microsoft software overview page.