UUCP Address Format:

The old UUCP (Unix-to-Unix Copy Program) method of sending messages over the
Internet is unreliable, slow, and awkward, but it was the standard way of
communicating over the Net back in the dark old days. UUCP addresses were
often called "bang paths", because items in them are separated by exclamation
marks, which are often called "bangs" in hackerdom.

The basic format of a UUCP address is very simple. In fact, it is nothing
more than a list of machines through which a message is meant to travel, with
each machine's name separated by an exclamation mark. So, the syntax is:

first_machine!machine!machine!users_machine!user

The first machine's name must be reachable from the current network; Thus,
well-known system names are used so that people will have access to the first
link in the chain. From there, the chain travels through progressively more
obscure systems, each reachable only through the previous link in the chain.

The first machine's name is often "uunet". So, you might have an address
like:

uunet!bigcompany!marketing!jim

This might route the message onto UUnet, into a company called "bigcompany",
to a machine called "marketing" (which, presumably, would be used by the
marketing department), and then finally to the user "jim".