For sending emails we have provided two events. Those events are commented right now. What you have to do is uncomment that code resides in OrderRepository.php file.
uncomment below two lines
// event(new OrderCreated($order));
// event(new OrderReceived($order));
Now what you need to do is run the queue. As this event will run in the queue you have to make sure your queue is running.
php artisan queue:work
The above command can be run to listen to the events. For details on this issue please check the below documentation from laravel.