src/Viserio/Component/Mail/Mailer.php
protected function shouldSendMessage(Swift_Mime_SimpleMessage $message): bool
    {
        if (! $this->eventManager) {
            return true;
        }

        return $this->eventManager->trigger(new MessageSendingEvent($this, $message)) !== false;
    }
protected function shouldSendMessage(Swift_Mime_SimpleMessage $message): bool
    {
        if (! $this->eventManager) {
            return true;
        }

        return $this->eventManager->trigger(new MessageSendingEvent($this, $message)) !== false;
    }
Determines if the message can be sent.

@param \Swift_Mime_SimpleMessage $message

@return bool