Swift mail working fine locally but not when i put it live, I've changed the path for my hosting and still not working

the following code from the video works fine

$transport = Swift_SendmailTransport::newInstance('/usr/sbin/sendmail -bs');

    $mailer = \Swift_Mailer::newInstance($transport);

    $message = \Swift_Message::newInstance();
    $message->setSubject('Message from ' . $cleanName);
    $message->setFrom(array(
        $cleanEmail => $cleanName
    ));
    $message->setTo(array('example@hotmail.com'));
    $message->setBody($cleanMessage);

    $result = $mailer->send($message);

    if($result > 0) {
        $app->redirect('/');
    } else {
        $app->redirect('contact');
    }

However when I put the site live I change the path to the one I think is provided by my host company this is the line in the hosting settings

Sendmail path /usr/local/bin/sendmail (SMTP is enabled, free type accounts may send up to 31 emails a month)

so it looks like this -

$transport = Swift_SendmailTransport::newInstance('/usr/local/bin/sendmail -bs');

I get slim application error as follows

Details

Type: Swift_TransportException Message: Expected response code 220 but got code "", with message "" File: /srv/disk7/1677892/www/tomcheckley.co.uk/vendor/swiftmailer/swiftmailer/lib/classes/Swift/Transport/AbstractSmtpTransport.php Line: 383

If anyone can explain I'd be much appreciative. Thanks!