queue_repair features include:
- automatic, dynamic determination of UIDs and GIDs.

- automatic, dynamic determination of conf-split; can be overridden on the
  commandline to change the conf-split of an existing queue without running a
  parallel, temporary instance of qmail for queuelifetime.  Just recompile and
  stop qmail, run queue-repair, and restart qmail.

- automatic, dynamic determination of use of big-todo; can be overridden on the
  commandline to change an existing queue as above.

- handles basic tasks like fixing a queue restored from backups, incorrect
  ownership or permissions of directories and files, missing or extra split
  subdirectories, unexpected files or other direntries, or creating a valid
  queue from scratch.

- can run in repair or test (report-only) modes.  The default is test mode.

WWW: http://pyropus.ca/software/queue-repair/