comment client de messagerie fonctionne?

NAME
     mbox - file containing mail messages

   INTRODUCTION
     The most common format for storage of mail messages is mbox
     format. An mbox is a single file containing zero or more
     mail messages.

   MESSAGE FORMAT
     A message encoded in mbox format begins with a From_ line,
     continues with a series of non-From_ lines, and ends with a
     blank line. A From_ line means any line that begins with
     the characters F, r, o, m, space:

        From god@heaven.af.mil Sat Jan 3 01:05:34 1996
        Return-Path: <god@heaven.af.mil>
        Delivered-To: djb@silverton.berkeley.edu
        Date: 3 Jan 1996 01:05:34 -0000
        From: God <god@heaven.af.mil>
        To: djb@silverton.berkeley.edu (D. J. Bernstein)

        How's that mail system project coming along?


     The final line is a completely blank line (no spaces or
     tabs). Notice that blank lines may also appear elsewhere in
     the message.

     The From_ line always looks like From envsender date
     moreinfo. envsender is one word, without spaces or tabs; it
     is usually the envelope sender of the message. date is the
     delivery date of the message. It always contains exactly 24
     characters in asctime format. moreinfo is optional; it may
     contain arbitrary information.

     Between the From_ line and the blank line is a message in
     RFC 822 format, as described in qmail-header(5), subject to
     >From quoting as described below.