public function loadRegisteredTemplates()
    {
        foreach ($this->callbacks as $callback) {
            $callback($this);
        }

        $plugins = PluginManager::instance()->getPlugins();
        foreach ($plugins as $pluginId => $pluginObj) {
            $layouts = $pluginObj->registerMailLayouts();
            if (is_array($layouts)) {
                $this->registerMailLayouts($layouts);
            }

            $templates = $pluginObj->registerMailTemplates();
            if (is_array($templates)) {
                $this->registerMailTemplates($templates);
            }

            $partials = $pluginObj->registerMailPartials();
            if (is_array($partials)) {
                $this->registerMailPartials($partials);
            }
        }
    }