CDO

Collaboration Data Objects (CDO) is Microsoft's technology for building messaging or collaboration applications or adding these capabilities to existing applications.
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.