post_install() {
  # create users
  if ! getent group smtpd &>/dev/null; then
    groupadd -r smtpd >/dev/null
  fi
  if ! getent group smtpq &>/dev/null; then
    groupadd -r smtpq >/dev/null
  fi
  if ! getent passwd smtpd &>/dev/null; then
    useradd -r -c "SMTP Daemon" -d /var/empty --uid 91 --gid smtpd --shell /bin/nologin smtpd >/dev/null
  fi
  if ! getent passwd smtpq &>/dev/null; then
    useradd -r -c "SMTP Queue" -d /var/empty --uid 92 --gid smtpq --shell /bin/nologin smtpq >/dev/null
  fi
  # Fix ownership of smtpctl
  chown smtpd:smtpq /usr/sbin/smtpctl
  chmod 2555 /usr/sbin/smtpctl
}

post_upgrade() {
  if (( $(vercmp $2 6.0.3p1-2.hyperbola3) < 0 )); then
    post_remove
  fi
  post_install
  if (( $(vercmp $2 5.3.3p1-1) < 0 )); then
    echo 'Configuration files have been moved to /etc/smtpd.'
    echo 'New users have been added.'
    echo 'Check your configuration!'
  elif (( $(vercmp $2 5.4) < 0 )); then
    echo 'User smtpf is no more required. It will be removed!'
    echo 'Check your configuration!'
    userdel -f smtpf >/dev/null
  fi
}

post_remove() {
  if getent passwd smtpd &>/dev/null; then
    userdel smtpd >/dev/null
  fi
  if getent passwd smtpq &>/dev/null; then
    userdel smtpq >/dev/null
  fi
  if getent group smtpd &>/dev/null; then
    groupdel smtpd >/dev/null
  fi
  if getent group smtpq &>/dev/null; then
    groupdel smtpq >/dev/null
  fi
}