To create an Administrator extension DLL, you use the Administrator extension functions and structures that are defined in the ADMINEXT.H file. Two main categories of functions are used to create an extension DLL:
Administrator extension functions (called by Administrator Program) You provide these functions in your Administrator extension DLL. The Microsoft Exchange Server Administrator program calls these functions to retrieve information about your property pages and to inform your extension DLL of events. For example, the CommitDataProc function is called when the Apply button is clicked, and tells the extension DLL to store its data permanently.
Administrator extension functions (called by extension DLL) This set of functions allows your extension DLL to communicate with the Administrator program. They are used to retrieve and save extension data. They also provide functionality that makes custom property pages behave like standard property pages displayed by the Administrator program.