160: How do I recover my mail files after RMAIL munges their format?
  
  Users who just want to try RMAIL out to see how it works end up trapped
  using it because saved mail in their `mbox' file has been converted into
  an incompatible format (BABYL) that only RMAIL understands.  RMAIL
  provides no obvious way to reverse this transformation.  To convert a mail
  file back to standard Unix format, there are several methods:
  
  * Use the rmail-output ("C-o") command within RMAIL on each message in the
    file.  First use M-x rmail or M-x rmail-input to visit the RMAIL file in
    Rmail mode.  Type "1 j" to go to the first message.  Use the C-o command
    to output the message to a Unix format file.  Type "n" to go to the next
    message.  Repeat.
  
  * If the file contains hundreds of messages, you may not want to repeat
    this for all of them.  Instead of the above, after getting to the first
    message type this (where "mbox" is the file you want to put the messages
    in):
  
      C-x ( C-o mbox RET M-s ^From: RET M-0 C-x )
  
    (The rmail-search command ("M-s") is used instead of just "n" because it
    is the only command which will cause an error when it reaches the last
    message in the file, which is necessary to terminate the keyboard macro.
    This will fail if there are messages in the file that don't have a
    `From:' header.  This assumes rmail-delete-after-output is nil.)
  
    It is wise to save a copy of the RMAIL file first, in case you make a
    mistake.
  
  * There are software packages available for converting files or even
    entire directories of BABYL files to standard Unix format.  These are
    helpful in this situation, but are intended mainly for people who have
    used RMAIL for a long time and are converting to some other mail reader.
    Lookup `rmail', `vm', and `babyl' in the Emacs Lisp Archive (see
    question 91).
  
  You may wish to disable RMAIL to avoid accidentally destroying your mbox
  file (I have this in my .emacs):
  
    (put 'rmail 'disabled t)		; avoid mbox destruction