public function smtp($host, $user, $pass, $port = null, $ssl = false, $tls = false)
    {
        Argument::i()
            ->test(1, 'string')
            ->test(2, 'string')
            ->test(3, 'string')
            ->test(4, 'int', 'null')
            ->test(5, 'bool')
            ->test(6, 'bool');
            
        return Smtp::i($host, $user, $pass, $port, $ssl, $tls);
    }