     Multics provides users with extensive means for communicating with one
another.  For the purpose of discussion here, we will distinguish two kinds of
communication: messages and mail (though elsewhere these terms are often used
interchangably).  Messages and mail are normally read on the computer
terminal, but they can also be printed out on a high-speed printer.

     Because they must be typed on a single "command line," messages are
usually short notes used for rapid communication.  They do not have subject
lines, and they do not list the recipients, even if there is more than one.

     Mail, on the other hand, is used as a letter would be--for longer
communications.  You can send and read mail with either the send_mail and
read_mail "commands" or with the Executive Mail facility (the latter is
available at most but not all Multics sites).  In either case, the mailbox in
which a user's mail is received is the same.  In fact, messages can also be
sent to this mailbox if you wish.
