public function Authorise ($host, $port = false, $tval = false, $username, $password, $debug_level = 0) {
    $this->host = $host;

    //  If no port value is passed, retrieve it
    if ($port == false) {
      $this->port = $this->POP3_PORT;
    } else {
      $this->port = $port;
    }

    //  If no port value is passed, retrieve it
    if ($tval == false) {
      $this->tval = $this->POP3_TIMEOUT;
    } else {
      $this->tval = $tval;
    }

    $this->do_debug = $debug_level;
    $this->username = $username;
    $this->password = $password;

    //  Refresh the error log
    $this->error = null;

    //  Connect
    $result = $this->Connect($this->host, $this->port, $this->tval);

    if ($result) {
      $login_result = $this->Login($this->username, $this->password);

      if ($login_result) {
        $this->Disconnect();

        return true;
      }

    }

    //  We need to disconnect regardless if the login succeeded
    $this->Disconnect();

    return false;
  }