Notice: This website is an unofficial Microsoft Knowledge Base (hereinafter KB) archive and is intended to provide a reliable access to deleted content from Microsoft KB. All KB articles are owned by Microsoft Corporation. Read full disclaimer for more details.

Support policy for Microsoft Exchange APIs with the .NET Framework applications

View products that this article applies to.


This article outlines the support policy for using various Exchange application programming interfaces in a Microsoft .NET Framework application. This article applies to all versions and service packs of both Microsoft Exchange Server 5.5 and Microsoft Exchange 2000 Server.

Microsoft is committed to providing the ability to programmatically access Exchange 2000 Server by using the latest available .NET technologies. If you build a .NET Framework application, the supported options for accessing Exchange data are:
  • WWW Distributed Authoring and Versioning (WebDAV) through HTTP requests and responses.
  • Collaboration Data Objects (CDO) for Exchange 2000 Server (CDOEX) and Exchange OLE DB provider (ExOLEDB) through an interop assembly.
  • Windows Management Instrumentation (WMI).
  • Collaboration Data Objects for Exchange Management (CDOEXM).
If the .NET application assemblies reside directly on the Exchange server, Microsoft recommends building the application by using CDOEX and ExOLEDB. If the .NET application assemblies do not reside directly on the Exchange Server, Microsoft recommends using WebDAV.

For .NET Framework applications that send mail without using Exchange Server as the transport, Microsoft CDO for Windows 2000 (CDOSYS) can be used through an interop assembly. However, Microsoft recommends using System.Web.Mail. System.Web.Mail is a managed wrapper to CDOSYS that enables you to construct and send messages by using the CDOSYS message component. The mail message is delivered either through the SMTP mail service that is built into Microsoft Windows 2000 or through an arbitrary SMTP server.

CDO 1.2x and MAPI are not supported in a .NET Framework environment. For CDO 1.2x and MAPI type functionality, use one of the supported access methods mentioned in the "Summary" section. For .NET Framework applications that must send mail without using Exchange Server as the transport, System.Web.Mail is a good option. However, Microsoft Collaboration CDOSYS can also be used through an interop assembly.

CDO 1.2x and MAPI are not supported in a .NET Framework environment.


Microsoft is committed to improving the .NET Framework environment and to making access to Exchange data from within that environment even easier. The supportability status of some of these components may change without notice.

The following table summarizes the support policy for Exchange APIs in a .NET environment:
APIDLL NameManaged Code Support Policy
CDOSYSCDOSYS.DLLSupported, but System.Web.Mail is recommended
CDOEXMCDOEXM.DLLSupported by using a COM interop assembly
EXOLEDBSupported by using a COM interop assembly
CDOEXCDOEX.DLLSupported by using a COM interop assembly
CDO 1.2xCDO.DLLNot Supported
MAPIMAPI32.DLLNot Supported
ESE Backup APIESEBCLI2.DLLNot Supported
Note All of the components that are listed in the table are fully supported in unmanaged Visual C++.

↑ Back to the top


For more information, visit the following MSDN Web sites:

.NET Interop: Get Ready for Microsoft .NET by Using Wrappers to Interact with COM-based Applications

Introduction to COM Interop

COM Interop Sample: .NET Client and COM Server

Advanced COM Interop

Handling COM Interop Exceptions

↑ Back to the top

Keywords: KB813349, kbhowto

↑ Back to the top

Article Info
Article ID : 813349
Revision : 13
Created on : 10/25/2007
Published on : 10/25/2007
Exists online : False
Views : 390