What Does Collaboration Data Objects (CDO) Mean?

Collaboration Data Objects (CDO) is an application programming interface (API) built into Microsoft Server products. CDO provides access to the global address list, mailbox content, public folders and other server objects related to messaging and Microsoft Outlook. CDO cannot be used to directly program added functionality to MS Outlook.

Techopedia Explains Collaboration Data Objects (CDO)

The Microsoft application programming interface (MAPI) is a flexible interface that is able to support new APIs and features for upcoming applications. CDO is a scripting interface added to the existing MAPI. CDO uses an object library, which not only supports C/C++ clients, but also supports any application that creates and accesses COM objects.