(Collaborative Data Objects) A programming interface from Microsoft for accessing MAPI-based e-mail, calendaring and scheduling servers. Originally called "OLE Messaging" and "Active Messaging," CDO wraps the Enhanced MAPI library into a COM object that provides the ability to dynamically create Web pages. CDO is server oriented whereas MAPI has a client orientation.

CDONTS (CDO for NT Server) is the SMTP version of CDO. It is widely used to send text e-mail and HTML-based e-mail from ASP pages. CDONTS was introduced with Internet Information Server 4 (IIS4) to make the Web server software fully Internet compliant.