6 Exchange Transport and Routing
While the Store is the heart of Exchange, the Transport engine is its lungs. In this chapter, we review how Exchange 2007 transports and routes messages from origination to destination.
In terms of flexibility, the way that messaging systems route email has evolved greatly over the last ten years. Mapping developments against the history of Exchange, a rough timeline is as follows:
Pre Exchange: Message routing is quite inflexible and administrators need to sit down and map out the path of messages from one server to another within an organization to understand how messages flow. ...