Introduction

[This is preliminary documentation and subject to change.]

The Microsoft© Windows 2000 SMTP and NNTP services provide a high performance, component-based event architecture for message processing, delivery, and relay. Unlike a monolithic service, these services can be extended through event sinks that can process a message as it passed through the system.

The event architecture is based upon the Component Object Model (COM). Sinks registered to handle events are simply COM objects that expose the appropriate COM interfaces. When a particular event occurs, the service creates an instance of the event sink COM class, requests to the appropriate interface, and executes the event method. To allow for high performance, multi-threaded sinks, the framework allows for either synchronous or asynchronous sink processing.