Issue #2848810 by webadpro, Perignon: Notice: Undefined index: Reply-To in...

Issue #2848810 by webadpro, Perignon: Notice: Undefined index: Reply-To in SendGridMailSystem->mail()

inc/sendgrid.mail.inc

@@ -281,7 +281,7 @@ class SendGridMailSystem implements MailSystemInterface {
           break;
 
         case 'reply-to':
-          if (isset($message['headers']['Reply-To']) || isset($message['headers']['reply-to']) && $message['headers']['reply-to'] = $message['headers']['Reply-To']) {
+          if (isset($message['headers']['reply-to']) || (isset($message['headers']['Reply-To']) && $message['headers']['reply-to'] = $message['headers']['Reply-To'])) {
             $sendgrid_message->setReplyTo($message['headers']['reply-to']);
           }