post_install() {
  #set up the /var/run directory
  systemd-tmpfiles --create /usr/lib/tmpfiles.d/courier-mta.conf

  # perform all the tasks required of a standard Courier install
  echo <<<EOF
To finish the installation, run:
$ /usr/lib/courier/sysconftool /etc/courier/*.dist
$ makealiases
$ makesmtpaccess
$ /usr/bin/mkdhparams
And don't forget to configure an account to receive postmaster mail!
EOF
}

pre_upgrade() {
  # the file courier-imapd.conf is renamed to courier-mta.conf from version 0.77.0-2
  [ -f /usr/lib/tmpfiles.d/courier-imapd.conf ] && rm -f /usr/lib/tmpfiles.d/courier-imapd.conf
  [ "${1%%.*}" = "1" ] && [ "${2%%.*}" != "1" ] && echo "Please make sure you have read the guidance on pre-unicode maildir names."
}

post_upgrade() {
  echo <<<EOF
Please run
$ /usr/lib/courier/sysconftool /etc/courier/*.dist
EOF
}

pre_remove() {
  # there may be many files not part of the original installation that would be useful to save
  # so save the whole configuration directory rather than try to list all possibilities
  # in backup().
  mv -f /etc/courier /etc/courier-$1
  echo "/etc/courier has been saved as /etc/courier-$1 - you may remove this folder if you wish."

  # clean up temporary storage
  rm -rf /run/courier /var/spool/courier
}