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APPLIES TO: 
2016 2019 
Subscription Edition
Tip
Looking for what's discontinued in Exchange Server 2019? See What's discontinued in Exchange Server 2019.
This topic discusses the components, features, and functionality that's been removed, discontinued, or replaced in Exchange Server Subscription Edition (SE).
Discontinued features from Exchange 2019 to Exchange SE
This section lists the Exchange 2019 features that are no longer available in Exchange SE.
Exchange Server Subscription Edition (SE) RTM is code equivalent to Exchange Server 2019 CU15, except for the following changes:
- The License agreement, an RTF file shown only in the GUI version of Setup, is different
- The product name changed from Microsoft Exchange Server 2019 to Microsoft Exchange Server Subscription Edition
- The build number
New changes are introduced starting with the Exchange Server SE Cumulative Update (CU) 1.
Discontinued features from Exchange 2016 to Exchange SE
This section lists the Exchange 2016 features that are no longer available in Exchange SE.
Architecture
| Feature | Comments and mitigation |
|---|---|
| Unified Messaging (UM) | Unified Messaging has been removed from Exchange SE. We recommend that Exchange SE organizations transition to Skype for Business Cloud Voice Mail. |
Discontinued features from Exchange 2013 to Exchange SE
This section lists the Exchange 2013 features that are no longer available in Exchange SE.
Architecture
| Feature | Comments and mitigation |
|---|---|
| Unified Messaging (UM) | Unified Messaging has been removed from Exchange SE. We recommend that Exchange SE organizations transition to Skype for Business Cloud Voice Mail. |
| Client Access server role | Client Access services that run on the Mailbox server role replaced the Client Access server role. The Mailbox server role now performs all functionality that was previously included with the Client Access server role. For more information about the new Mailbox server role, see Exchange Server architecture. |
| MAPI/CDO library | The MAPI/CDO library was replaced by Exchange Web Services (EWS), Exchange ActiveSync (EAS), and Representational State Transfer (REST) APIs. If an application uses the MAPI/CDO library, it needs to move to EWS or EAS to communicate with Exchange SE. |
De-emphasized features in Exchange SE
The following features are being de-emphasized in Exchange SE and may not be included in future versions of Exchange.
Third-party replication APIs
RPC over HTTP
Database availability group (DAG) support for failover cluster administrative access points