MESSAGE DATA BASE

The message data base resides in the mail  spool  directory  (de-
fined  with  the MAILDIR environment variable). There are various
classes of message files:

 - mail received from the network

 - mail ready to send over the network

 - messages in preparation

In addition there are administrative files (LOGFILE,  alias  data
base and communications parameters).

Each message takes two files: a data file (with the  actual  mes-
sage)  and a meta file (with originator or destination addresses,
or a one-line summary in case of a message in preparation).

Data/meta file names are constructed by concatenating  a  single-
character prefix with a five-digit sequence number. Corresponding
data and meta files have the same  sequence  number.  The  prefix
characters are:

 E message in preparation
 C description of message

 N message received from the net
 H originator address in case of an unread message
 O originator address in case of already read message

 D message ready to be sent over the net
 X destination of that message.

Administrative files are

 LOGFILE transaction log
 s00000 communications parameters
 a00000 alias data base

All files in the mail directory are ordinary text files,  with  a
possible  exception  for the message in preparation (this depends
on the editor being used).

Files in the  mail  directory  are  normally  write-protected  to
prevent accidents.

