public function getOAUTHInstance()
    {
        if (!is_object($this->oauth)) {
            $this->oauth = new PHPMailerOAuthGoogle(
                $this->oauthUserEmail,
                $this->oauthClientSecret,
                $this->oauthClientId,
                $this->oauthRefreshToken
            );
        }
        return $this->oauth;
    }