Upgrading to Microsoft Exchange 2000 Server

When you upgrade a computer running Microsoft® Windows® 2000 with Microsoft® Exchange® 2000 server, a new COM component, Microsoft CDO for Exchange 2000 replaces the Microsoft CDO for Windows 2000 component. The CDO for Windows 2000 component is a proper subset of the functionality offered by CDO for Exchange 2000, so all applications, including transport event sinks, will continue to function properly. When Microsoft Exchange 2000 is installed, the CDO for Windows 2000 component is unregistered from the system and COM runtime.

Both components share a common set of GUID values, interface definitions, enumerations, module constants and so on. Applications written in Microsoft Visual Basic, Microsoft J++, or Microsoft Visual C++ do not need to be re-compiled. The application will simply load the new CDO for Exchange 2000 component at runtime.

You need to redesign any application using CDO for Windows 2000 if it uses the drop directory provided by the SMTP or NNTP services on the machine. When Microsoft Exchange 2000 is installed, the Exchange Web Store becomes the drop location for messages and NNTP posted files on the server; the SMTP and NNTP services no longer drop messages to the SMTP/NNTP drop directory.