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

       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 mes... September 2023                                EXIM_ID_UPDATE(8)

       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.

       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.

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

-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.

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