source route

messaging An electronic mail address which specifies the

route the message should take as a sequence of hostnames.

It is called a source route because the route is determined at

the source of the message rather than at each stage as is now

more common. The most common kind of source route is a UUCP

style bang path, "foo!bar!baz!fred'. The RFC 822 syntax,

"@foo:@bar:fred@baz", is seldom seen because most systems

which understand RFC 822 also perform automatic routing based

on the destination hostname. A third, intermediate, form is

sometimes seen: "fred%baz%[email protected]".