From: Ron Bickers <rbickers@logicetc.com>

For the archives (or for comment):

I now have mailbox_command = /usr/local/libexec/postqmail-local and
postqmail-local looks like this (minus some mailer wrapping):

  #!/bin/sh
  export PATH=$PATH:/usr/local/bin:/var/qmail/bin
  tail +2 | seekablepipe qmail-local -- \
    "$USER" "$HOME" "$LOCAL" "${EXTENSION:+-}" "$EXTENSION"
    "$DOMAIN""$SENDER" ./Maildir/
  e=$?
  (($e == 111)) && exit 75
  (($e == 100)) && exit 77
  exit $e