The Microsoft Exchange Server MAPI Client and Collaboration Data Objects 1.2.1 version 6.5.8165.0 are now available to download.
Starting with Exchange 2007, neither the Messaging API (MAPI) client libraries nor CDO 1.2.1 are provided as a part of the base product installation. As a result, there is functionality missing that many applications depend on. Microsoft Exchange MAPI and CDO 1.2.1 provide access to these APIs
The Messaging API is a COM-like API that provides access to the contents of messaging stores. CDO 1.2.1 (Collaboration Data Objects, version 1.2.1) is a package providing access to Outlook-compatible objects through a COM-based API. Using either CDO or MAPI, a program can connect to a MAPI store, and then perform operations against that store. Starting with Exchange 2007, Microsoft will distribute the MAPI client libraries and CDO 1.2.1 as a Web download.