  public function Login ($username = '', $password = '') {
    if ($this->connected == false) {
      $this->error = 'Not connected to POP3 server';

      if ($this->do_debug >= 1) {
        $this->displayErrors();
      }
    }

    if (empty($username)) {
      $username = $this->username;
    }

    if (empty($password)) {
      $password = $this->password;
    }

    $pop_username = "USER $username" . $this->CRLF;
    $pop_password = "PASS $password" . $this->CRLF;

    //  Send the Username
    $this->sendString($pop_username);
    $pop3_response = $this->getResponse();

    if ($this->checkResponse($pop3_response)) {
      //  Send the Password
      $this->sendString($pop_password);
      $pop3_response = $this->getResponse();

      if ($this->checkResponse($pop3_response)) {
        return true;
      }
    }
    return false;
  }
The product receives input or data, but it does
        not validate or incorrectly validates that the input has the
        properties that are required to process the data safely and
        correctly.