preg_replace(): The /e modifier is deprecated.

System throw a warning sending mails:

Deprecated function: preg_replace(): The /e modifier is deprecated, use preg_replace_callback instead in Drupal\smtp\PHPMailer\PHPMailer->EncodeQ() (line 1762 of modules/contrib/smtp/src/PHPMailer/PHPMailer.php).

  public function EncodeQ($str, $position = 'text') {
    // There should not be any EOL in the string
    $encoded = preg_replace('/[\r\n]*/', '', $str);

    switch (strtolower($position)) {
      case 'phrase':
        $encoded = preg_replace("/([^A-Za-z0-9!*+\/ -])/e", "'='.sprintf('%02X', ord('\\1'))", $encoded);
        break;
      case 'comment':
        $encoded = preg_replace("/([\(\)\"])/e", "'='.sprintf('%02X', ord('\\1'))", $encoded);
      case 'text':
      default:
        // Replace every high ascii, control =, ? and _ characters
        //TODO using /e (equivalent to eval()) is probably not a good idea
        $encoded = preg_replace('/([\000-\011\013\014\016-\037\075\077\137\177-\377])/e',
              "'='.sprintf('%02X', ord('\\1'))", $encoded);
        break;
    }

    // Replace every spaces to _ (more readable than =20)
    $encoded = str_replace(' ', '_', $encoded);

    return $encoded;
  }