allow scheme to be specified

Author: taylorotwell

src/Illuminate/Mail/MailManager.php

@@ -171,10 +171,16 @@ protected function createSmtpTransport(array $config)
     {
         $factory = new EsmtpTransportFactory;
 
-        $transport = $factory->create(new Dsn(
-            ! empty($config['encryption']) && $config['encryption'] === 'tls'
+        $scheme = $config['scheme'] ?? null;
+
+        if (! $scheme) {
+            $scheme = ! empty($config['encryption']) && $config['encryption'] === 'tls'
                 ? (($config['port'] == 465) ? 'smtps' : 'smtp')
-                : '',
+                : '';
+        }
+
+        $transport = $factory->create(new Dsn(
+            $scheme,
             $config['host'],
             $config['username'] ?? null,
             $config['password'] ?? null,