class Mailer

final class Mailer implements MailerInterface {
    public function __construct(TransportInterface $transport, ?MessageBusInterface $bus = null, ?EventDispatcherInterface $dispatcher = null) {
    }
    public function send(RawMessage $message, ?Envelope $envelope = null) : void {
        if (null === $this->bus) {
            $this->transport
                ->send($message, $envelope);
            return;
        }
        $stamps = [];
        if (null !== $this->dispatcher) {
            // The dispatched event here has `queued` set to `true`; the goal is NOT to render the message, but to let
            // listeners do something before a message is sent to the queue.
            // We are using a cloned message as we still want to dispatch the **original** message, not the one modified by listeners.
            // That's because the listeners will run again when the email is sent via Messenger by the transport (see `AbstractTransport`).
            // Listeners should act depending on the `$queued` argument of the `MessageEvent` instance.
            $clonedMessage = clone $message;
            $clonedEnvelope = null !== $envelope ? clone $envelope : Envelope::create($clonedMessage);
            $event = new MessageEvent($clonedMessage, $clonedEnvelope, (string) $this->transport, true);
            $this->dispatcher
                ->dispatch($event);
            $stamps = $event->getStamps();
            if ($event->isRejected()) {
                return;
            }
        }
        try {
            $this->bus
                ->dispatch(new SendEmailMessage($message, $envelope), $stamps);
        } catch (HandlerFailedException $e) {
            foreach ($e->getWrappedExceptions() as $nested) {
                if ($nested instanceof TransportExceptionInterface) {
                    throw $nested;
                }
            }
            throw $e;
        }
    }

}