Mail is the single program in this directory.  Its argument specifies
the mail box to read, default /mail/box/$user/mbox.
For example, running
	Mail /mail/box/$user/stored
(a line in the guide file) looks at saved mail.

Mail maintains a window containing headers for all the
messages in the mailbox and monitors the mailbox for new messages.
Using button 3 to indicate a message number opens
a window on that message.   commands in the mailbox window are
	Put		Write the mailbox back to the file (never done automatically)
	Mail		Make a new message window ready to mail someone.
			Takes argument names analogously to acme's New.
	Del		Exit Mail, after checking that mailbox isn't modified.
New messages appear at the top of the window and are highlighted upon arrival.
(The messages are numbered oldest to newest, the opposite of regular mail.)

Message windows have a simple format: the first line, up to the first tab or newline,
holds the sender or, when sending, the addressee.  Edit the line to change who the
message goes to.  Message windows contain the commands
	Reply	Make a new window to compose a reply to this message
	Delmesg	Delete the message from the screen and from the mailbox
	Del		Delete the window, leaving the message in the mailbox
	Post		Send the message to the addressee
	Save		Save to the named mailbox, default/mail/box/$user/stored
Save takes a full file name; if that name has no slashes, the file is taken
to be in /mail/box/$user and must already exist. Use mkbox in the guide to
create target mailboxes in /mail/box/$user.
Reply and mail windows contain an obvious subset of the commands.
