An exceptional article on CodeProject detailing an extensible mass emailing framework using the MS SQL Server 2005 Service Broker.
I'm not sure about the IM-conversation style of writing, but that's just taste. The content is first-rate.
What's the Service Broker?
Service Broker is a new feature of Microsoft® SQL Server 2005. It offers asynchronous messaging support, and is tightly integrated with the SQL Server database engine. Service Broker provides a new, queue-based durable messaging framework which can send and receive messages between service endpoints, such as server instances, databases, and .NET 2.0 clients. Messages can be up to 2 GB in size, and can use the varbinary or varbinary(max) data types. I have blogged some links and resources for SSB. Looking at these links will be good starting point.