Collaboration Data Objects (CDO) is Microsoft's technology for building messaging or collaboration applications or adding these capabilities to existing applications. Part of the Microsoft Exchange Server product, CDO has evolved from what Microsoft formerly called Object Linking and Embedding Messaging and, more recently, Active Messaging. Using Active Server Page (ASP) technology with CDO, a Web site builder can, for example, write a script that will exchange e-mail with users or with other Web sites, collaborate in discussions on other Web sites, or allow employees to schedule meetings with multiple recipients, review existing appointments, schedule new events, and so forth.
CDO is really an additional scripting interface to an existing Microsoft messaging model, the Messaging Application Programming Interface (MAPI). Collaborative Data Objects are made available through two CDO libraries. These libraries let you address programmable messaging objects (including folders, messages, recipient addresses, attachments, and other messaging components). These objects are extensions to the programmable objects, such as forms and controls, that are offered as part of Microsoft's Visual Basic program development environment.