private function get_lines() {
    $data = "";
    while($str = @fgets($this->smtp_conn,515)) {
      if($this->do_debug >= 4) {
        echo "SMTP -> get_lines(): \$data was \"$data\"" . $this->CRLF . '<br />';
        echo "SMTP -> get_lines(): \$str is \"$str\"" . $this->CRLF . '<br />';
      }
      $data .= $str;
      if($this->do_debug >= 4) {
        echo "SMTP -> get_lines(): \$data is \"$data\"" . $this->CRLF . '<br />';
      }
      // if 4th character is a space, we are done reading, break the loop
      if(substr($str,3,1) == " ") { break; }
    }
    return $data;
  }