We wanted to write an article related to a very frequent customer question related to Exchange Server 2019 to Exchange Server Subscription Edition (SE) migration.
As we mentioned in Upgrading your ...
Updated May 02, 2025
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Blog Post
Dear Microsoft Support Team,
We are in the planning phase of migrating our existing on-premises Exchange Server 2016 environment to the Exchange Server Subscription Edition (SE) model.
Before proceeding, we’d like to validate certain technical and licensing aspects to ensure a smooth and compliant transition.
Environment Overview (for context):
Current Version: Exchange Server 2016 CU
Topology: Hybrid with Microsoft 365
Approx. Mailboxes: ~9 on prem mailboxes
OS Version: Windows Server 2019
Below are the key points where we seek Microsoft’s guidance or confirmation:
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1. Licensing and Subscription Model
What are the licensing implications for organizations currently running Exchange Server 2016 with Software Assurance?
Are there any new Client Access License (CAL) requirements under the SE model?
How does subscription renewal work for Exchange SE — annually or per user/device?
Will hybrid customers with Microsoft 365 require any additional licensing considerations?
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2. Upgrade and Migration Path
What are the supported migration or upgrade paths from Exchange 2016 to SE (e.g., in-place vs. side-by-side deployment)?
What are the minimum system prerequisites — Windows Server version, .NET Framework, schema updates, etc.?
Can coexistence between Exchange 2016 and SE be maintained during migration?
Is there a Microsoft-recommended rollback plan or checklist for potential migration issues?
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3. Infrastructure and Integration
Are there any changes to Active Directory forest/domain requirements?
Will Exchange SE continue to support hybrid coexistence with Microsoft 365?
Are existing PowerShell scripts, transport rules, and connectors compatible with SE?
Any impact expected on SMTP relay, load balancers, or Edge Transport servers?
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4. Security and Supportability
What is the expected update cadence for Exchange SE (cumulative updates, security patches)?
Does SE introduce any changes related to TLS 1.3, OAuth2, or DKIM/DMARC support?
Are there new baseline security or hardening recommendations specific to SE?
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5. Backup, Recovery, and Monitoring
Are standard backup and restore tools (VSS or third-party) supported with SE?
Is Managed Availability still present in SE for monitoring and recovery?
Any new event logs or telemetry differences compared to Exchange 2016?
- Nino_Bilic
Microsoft
It is a bit unclear to me what this post is about as many of those answers are the same as for Exchange 2019 and are basically all covered in documentation, but let me give it a crack:
- Please see the following on licensing, subscription model, upgrade and migration paths: Upgrading your organization from current versions to Exchange Server SE | Microsoft Community Hub
- Exchange SE prerequisites: https://learn.microsoft.com/en-us/Exchange/plan-and-deploy/prerequisites
- Exchange SE system requirements: Exchange Server 2019 and SE system requirements— memory requirements and client compatibility | Microsoft Learn
- Exchange Supportability Matrix: Exchange Server supportability matrix | Microsoft Learn
- Exchange SE AD schema changes: Active Directory schema changes in Exchange Server SE | Microsoft Learn
- Yes, Exchange SE continues supporting Hybrid
- Yes, on scripts etc. note that for a hybrid environment you will need to recreate connectors for Exchange SE as you will need to decommission Exchange 2016. Decommissioning Exchange Server 2016 | Microsoft Community Hub
- Exchange SE, just like Exchange 2019, supports SMTP relay, LB and Edge
- We plan to update Exchange SE with two Cumulative Updates a year, just like Exchange 2019 was. We release Security or Hotfix Updates as needed. Exchange Server update FAQ | Microsoft Learn
- On TLS: Exchange Server TLS configuration best practices | Microsoft Learn
- On OAuth: Enable Modern Auth in Exchange Server on-premises | Microsoft Learn
- No news on DKIM/DMARC for on-premises as of yet
- Yes, on standard backup still working
- Yes, on management availability
- Nothing major on logs / telemetry; same as Exchange 2019
