Try using smtp like this:
$message = new \Zend\Mail\Message();
$message->setBody('This is the body');
$message->setFrom('myemail@mydomain.com');
$message->addTo('someone@somedomain.com');
$message->setSubject('Test subject');
$smtpOptions = new \Zend\Mail\Transport\SmtpOptions();
$smtpOptions->setHost('smtp.gmail.com')
->setConnectionClass('login')
->setName('smtp.gmail.com')
->setConnectionConfig(array(
'username' => 'YOUR GMAIL ADDRESS',
'password' => 'YOUR PASSWORD',
'ssl' => 'tls',
));
$transport = new \Zend\Mail\Transport\Smtp($smtpOptions);
$transport->send($message);