Microsoft ended extended support for Exchange Server 2016, Exchange Server 2019, Skype for Business Server 2015 and Skype for Business Server 2019 in October 2025. Microsoft’s customer notice gives October 14, 2025 as the end date; product lifecycle tables show October 15, 2025 in Pacific Time. These server installations no longer receive Microsoft security updates, non-security updates, bug fixes or technical support.
Which products are now unsupported?
| Product | Mainstream support ended | Extended support ended |
|---|---|---|
| Exchange Server 2019 | January 10, 2024 | October 15, 2025 in Microsoft’s lifecycle table |
| Exchange Server 2016 | Not separately stated in the cited roadmap | October 14, 2025 in Microsoft’s customer-facing notice |
| Skype for Business Server 2019 | January 10, 2024 | October 15, 2025 in Microsoft’s lifecycle table |
| Skype for Business Server 2015 | October 14, 2020 | October 15, 2025 in Microsoft’s lifecycle table |
The one-day difference is a time-zone and publishing distinction, not a separate grace period. In practical terms, organizations should treat these releases as unsupported from October 14, 2025.
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What end of support changes
Microsoft’s notice says that after October 14, 2025, the affected Exchange releases no longer receive security updates, non-security updates, stability or usability bug fixes, or technical support. Microsoft applies the same end-of-support principle to the listed Skype for Business Server releases.
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- Product defects and reliability problems are no longer eligible for normal bug-fix support.
- Microsoft support cannot provide standard troubleshooting or corrective assistance for the unsupported server releases.
- Keeping a server running is technically possible, but the organization assumes the resulting security, compliance and operational risk.
Exchange customers: choose a supported destination
Microsoft identifies two supported directions for organizations leaving Exchange Server 2016 or 2019: Exchange Online through Microsoft 365, or Exchange Server Subscription Edition for organizations that must retain an on-premises deployment.
#1 Best Overall
- 64 bit | 1 Server with 16 or less processor cores | provides 2 VMs
- For physical or minimally virtualized environments
- Requires Windows Server 2025 User and/or Device Client Access Licenses (CALs) | No CALs are included
- Core-based licensing | Additional license packs required for servers with more than 16 processor cores or to add VMs | 2 VMs whenever all processor cores are licensed.
- Product ships in plain envelope | Activation key is located under scratch-off area on label |Beware of counterfeits | Genuine Windows Server software is branded by Microsoft only.
Exchange Online and Microsoft 365
Exchange Online moves mailbox hosting and much of the platform maintenance into Microsoft’s cloud. The organization must still plan identity, mail flow, authentication, mobile and desktop clients, retention, legal hold, backup strategy, security controls and integrations with line-of-business systems.
This path is generally the stronger fit when reducing server patching and datacenter operations is more important than retaining complete control over infrastructure. It requires a migration project rather than a simple version upgrade: inventory every mailbox and shared mailbox, discover applications that submit or relay mail, validate DNS and authentication changes, test coexistence, and schedule user cutovers.
Rank #2
- Offers quick and easy installation on PC
- The software is licensed for 5 User CAL
Exchange Server Subscription Edition
Exchange Server Subscription Edition began on July 1, 2025 and is supported under Microsoft’s Modern Lifecycle Policy. It preserves an on-premises operating model for organizations with regulatory, data-residency, latency, integration or operational requirements that make a cloud move unsuitable.
On-premises control also means continuing responsibility for servers, storage, high availability, certificates, monitoring, backups, incident response and security patch deployment. It is a supported route, not an end to lifecycle work: Microsoft says dates and supported versions can change under the Modern Lifecycle Policy. Microsoft’s additional-support policy says Exchange Server Subscription Edition will not reach end of support before December 31, 2035, subject to that policy.
Rank #3
- Server 2022 Standard 16 Core
Skype for Business customers: Teams or a subscription edition
Microsoft Teams
Microsoft recommends moving Skype for Business Server users to Microsoft Teams for cloud collaboration. A Teams migration affects chat, meetings, calling, conferencing, compliance, identity and user training, so organizations should map existing Skype policies and integrations before changing modes.
Assess telephone numbers and emergency calling, session border controllers, meeting-room devices, contact-center or recording systems, federation, compliance recording and retention. Pilot representative departments, verify network performance and establish a rollback or incident plan for the cutover window.
Rank #4
- 64 bit | 1 Server with 24 or less processor cores | provides 2 VMs
- For physical or minimally virtualized environments
- Requires Windows Server 2025 User and/or Device Client Access Licenses (CALs) | No CALs are included
- Core-based licensing | Additional license packs required for servers with more than 16 processor cores or to add VMs | 2 VMs whenever all processor cores are licensed.
- Product ships in plain envelope | Activation key is located under scratch-off area on label |Beware of counterfeits | Genuine Windows Server software is branded by Microsoft only.
Skype for Business Server Subscription Edition
Skype for Business Server Subscription Edition also began on July 1, 2025 and remains a supported on-premises option. It is intended for organizations that need local control or have dependencies that cannot yet move to Teams.
As with the Exchange subscription edition, the organization continues to operate and secure the infrastructure. Microsoft’s additional-support policy says Skype for Business Server Subscription Edition will not reach end of support before December 31, 2035, although the Modern Lifecycle Policy allows dates and supported-version requirements to change.
Best Value
- Unlock all the features by installing this product on PC
- The software is licensed for 1 User CAL
Do not confuse Skype for Business LTSC 2021 with the retired releases
Skype for Business LTSC 2021 has a separate lifecycle. Its scheduled support end date is October 13, 2026. That deadline does not extend support for Skype for Business Server 2015 or 2019, which already passed their October 2025 end date.
Quick Recap
How to decide between cloud and on-premises
| Decision factor | Cloud route | On-premises subscription route |
|---|---|---|
| Infrastructure control | Less control over underlying servers; Microsoft operates the service. | Maximum control over systems, network placement and maintenance windows. |
| Operating responsibility | Less server patching and hardware administration, but tenant configuration and security remain the customer’s responsibility. | Customer operates, patches, monitors, backs up and secures the deployment. |
| Regulatory and residency needs | Must be validated against the selected Microsoft 365 or Teams service configuration and applicable region. | May better fit requirements for local processing or tightly controlled environments. |
| Migration complexity | Requires identity, data, mail-flow or collaboration migration and integration testing. | Requires a supported-version deployment, coexistence or cutover planning, and continuing infrastructure work. |
| Cost model | Recurring cloud subscriptions and possible migration or integration costs. | Subscription licensing plus continuing datacenter, hardware, staffing and maintenance costs. |
| Lifecycle tolerance | Fewer product servers to replace, but service plans and tenant changes must be managed. | Retains another server lifecycle and future upgrade obligations. |
What administrators should do now
- Confirm exposure. Inventory every Exchange and Skype for Business server, edition, cumulative update, published endpoint and dependent application.
- Classify business constraints. Document residency, regulatory, connectivity, latency, telephony, archiving, relay and integration requirements.
- Select a target path. Evaluate Exchange Online versus Exchange Server Subscription Edition, and Teams versus Skype for Business Server Subscription Edition.
- Build a migration plan. Include identity synchronization, coexistence, data movement, DNS, certificates, network capacity, client versions, testing, communications and rollback.
- Reduce interim risk. Restrict administrative access, remove unnecessary internet exposure, enforce strong authentication around management systems, monitor suspicious activity and accelerate the move off unsupported servers.
- Validate the completed state. Confirm mail flow, meetings, calling, compliance controls, backups, monitoring and incident procedures before decommissioning the legacy environment.
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