The process of directing a message to the recipient's host is called
routing. Apart from finding a path from the sending site to the
destination, it involves error checking as well as speed and cost
optimization.
There is a big difference between the way a UUCP site handles routing,
and the way an Internet site does. On the Internet, the main job of
directing data to the recipient host (once it is known by it's
IP-address) is done by the IP networking layer, while in the UUCP zone,
the route has to be supplied by the user, or generated by the mail
transfer agent.
