Foi recentemente disponibilizada pela Microsoft uma actualização dos SDK's de Exchange 2000 e 2003.
The Exchange 2000/2003 Server SDK Documentation and Samples assist developers building applications for Exchange 2000 Server. This release of the SDK provides new and updated information and sample code to help you develop collaborative enterprise applications with Exchange. Included in this release are updates to the SDK documentation, tasks for implementing managed store event sinks, procedures for building managed event sink DLLs, and a task for getting free/busy status over HTTP.
Aqui ficam os links: