The Acme Mail program uses upas/fs to parse the mail box, and then
presents a file-browser-like user interface to reading and sending
messages.  The Mail window presents each numbered message like the
contents of a directory presented one per line.  If a message has a
Subject: line, that is shown indented on the following line.
Multipart MIME-encoded messages are presented in the obvious
hierarchical format.

Mail uses upas/fs to access the mail box.  By default it reads "mbox",
the standard user mail box.  If Mail is given an argument, it is
passed to upas/fs as the name of the mail box (or upas/fs directory)
to open.

Although Mail works if the plumber is not running, it's designed to be
run with plumbing enabled and many of its features work best if it is.

The mailbox window has a few commands: Put writes back the mailbox;
Mail creates a new window in which to compose a message; and Delmesg
deletes messages by number.  The number may be given as argument or
indicated by selecting the header line in the mailbox window.
(Delmesg does not expand null selections, in the interest of safety.)

Clicking the right button on a message number opens it; clicking on
any of the subparts of a message opens that (and also opens the
message itself).  Each message window has a few commands in the tag
with obvious names: Reply, Delmsg, etc.  "Reply" replies to the single
sender of the message, "Reply all" or "Replyall" replies to everyone
in the From:, To:, and CC: lines.

Message parts with recognized MIME types such as image/jpeg are sent
to the plumber for further dispatch.  Acme Mail also listens to
messages on the seemail and showmail plumbing ports, to report the
arrival of new messages (highlighting the entry; right-click on the
entry to open the message) and open them if you right-click on the
face in the faces window.

When composing a mail message or replying to a message, the first line
of the text is a list of recipients of the message.  To:, and CC:, and BCC:
lines are interpreted in the usual way. Two other header lines are
special to Acme Mail:
        Include: file places a copy of file in the message as an
		inline MIME attachment.
        Attach: file places a copy of file in the message as a regular
		MIME attachment.

Acme Mail uses these conventions when replying to messages,
constructing headers for the default behavior.  You may edit these to
change behavior.  Most important, when replying to a message Mail will
always Include: the original message; delete that line if you don't
want to include it.

If the mailbox
	/mail/box/$user/outgoing
exists, Acme Mail will save your a copy of your outgoing messages
there.  Attachments are described in the copy but not included.

The -m mntpoint flag specifies a different mount point for /upas/fs.