n. Online networks that are not part of the Internet.
But CD-ROMs aren't the only way people are getting acquainted with multimedia. Millions are using modems and analog telephone lines to log on to the expanding collection of online multimedia resources — World Wide Web home pages on the Internet and "outernet" services such as CompuServe, America Online and Prodigy.
—Christine Perey, “Multimedia moving toward the mainstream,” Business Communications Review, April 01, 1995
1992 (earliest)
For many users electronic mail is the most important and frequently used service of the Internet. Via E-mail users can exchange messages with any of the several million people directly connected to the Internet as well as an estimated two to four times that many on the "Outernet," an informal name for networks and E-mail systems that can exchange messages with the Internet.
—Daniel Dern, “Internet system experiencing meteoric growth,” InfoWorld, September 21, 1992