--- settings.php	2008-06-12 18:12:14.000000000 +0900
+++ settings.php	2008-06-12 18:13:57.000000000 +0900
@@ -226,3 +226,11 @@
 #   'forum'      => 'Discussion board',
 #   '@count min' => '@count minutes',
 # );
+
+function custom_url_rewrite_outbound(&$path, &$options, $original_path) {
+
+  if (module_exists('subdomain')) {
+    subdomain_url_rewrite($path, $options);
+  }
+
+}