NAME

       exim_id_update - one-time down/upgrade of Exim message-id formats

DESCRIPTION

       Utility for one-time down/upgrade of Exim message-id formats in spool files between format
       used in 4.96 and earlier and  4.97  and  later  versions.   Only  the  filenames  and  the
       first-line  ID  tag  values  are  affected; not message content such as Message-ID fields.
       Only -H, -D and -J files are handled.

SYNOPSIS

       exim_id_update [-d | -u | -h | -v] [spooldir]

OPTIONS

       -d     Downgrade mode

       -h     This help message

       -u     Upgrade mode

       -v     Version

       Exactly one of -d or -u must be given.  The spool directory  defaults  to  the  build-time
       value, or can be given as a command-line argument.

BACKGROUND

       The internal exim message ID format changed in 4.97:

       Change  format  of  the  internal ID used for message identification. The old version only
       supported 31 bits for a PID element;  the  new  64  (on  systems  which  can  use  Base-62
       encoding,  which  is  all currently supported ones but not Darwin (MacOS) or Cygwin, which
       have case-insensitive filesystems and must use Base-36).  The  new  ID  is  23  characters
       rather  than  16,  and  is  visible in various places - notably logs, message headers, and
       spool file names.  Various of the ancillary utilities also have to know the format.

       As well as the expanded PID portion, the sub-second part of the time recorded in the ID is
       expanded  to  support  finer  precision.  Theoretically this permits a receive rate from a
       single comms channel of better than the previous 2000/sec.

       The major timestamp part of the ID is not changed; at 6  characters  it  is  usable  until
       about year 3700.

       Updating  from  previously  releases  is fully supported: old-format spool files are still
       usable, and the utilities support both formats.  New message will use the new format.  The
       one  hints-DB  file type which uses message-IDs (the transport wait- DB) will be discarded
       if an old-format ID is seen; new ones will be built with only new-format IDs.

       Optionally, a utility can be used to convert spool files from old to new, but this is only
       an efficiency measure not a requirement for operation.

       Downgrading  from new to old requires running a provided utility, having first stopped all
       operations.  This will convert any spool files from new back to old (losing time-precision
       and PID information) and remove any wait- hints databases.

AUTHOR

       This  manual page was stitched together from help2man output and Exim changelog entry 4.97
       JH/29 by Andreas Metzler <ametzler at debian.org>, for the Debian  GNU/Linux  system  (but
       may be used by others).

Utility for one-time down/upgrade of Exim Septemberd2023mats                    EXIM_ID_UPDATE(8)