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. This version is the first release on CNET Download.com.