Message Service Parameter

In some cases, your extension might be designed to work only with a particular provider and this information should be included in the registration entry. For example, your extension might only work with a custom address book provider that replaces or supplements the default address book provider of Microsoft Exchange. Under these circumstances, your extension should be prevented from loading if its associated provider is not loaded.

This situation is handled by specifying the name of the extension’s associated provider in the [Provider] parameter of your extension’s registration line. If you specify the provider, your extension will not be loaded unless the provider has been loaded. This can save some programming effort because it might be difficult for your extension to determine whether a specific provider has been loaded. Frequently, but not as a requirement, these extensions are in the same DLL as the message service.

When Microsoft Exchange starts, it reads the current profile and attempts to start all providers listed there. After attempting to load all providers specified in the profile, it reads the extension registration lines of its .INI file or registry and omits all extensions that specify a provider that was not in the profile or failed to load.