public function test_smtp_connection() {
        // Check if user has permission
        if (!current_user_can('manage_options')) {
            wp_send_json_error('Access denied');
            return;
        }
        
        // Get test email from request
        $test_email = sanitize_email($_POST['test_email'] ?? '');
        if (empty($test_email)) {
            wp_send_json_error('Email address required');
            return;
        }
        
        // Test the email sending
        $result = $this->send_welcome_email($test_email, 'Test User', true);
        $errors = $this->get_last_smtp_errors();{"id":214,"count":1,"description":"","link":"https:\/\/om.makanluban.com\/en\/product-category\/wholesale\/","name":"Wholesale","slug":"wholesale","taxonomy":"product_cat","parent":0,"meta":[],"_links":{"self":[{"href":"https:\/\/om.makanluban.com\/en\/wp-json\/wp\/v2\/product_cat\/214","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/om.makanluban.com\/en\/wp-json\/wp\/v2\/product_cat"}],"about":[{"href":"https:\/\/om.makanluban.com\/en\/wp-json\/wp\/v2\/taxonomies\/product_cat"}],"wp:post_type":[{"href":"https:\/\/om.makanluban.com\/en\/wp-json\/wp\/v2\/product?product_cat=214"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}