--- user_mailman_register.module	(revision 9431)
+++ user_mailman_register.module	(working copy)
@@ -550,6 +550,22 @@

   $output .= l(t('Add new mailing list'), 'admin/settings/mailman_manager/add', array('query' => drupal_get_destination()));

+  $output .= '<br /><a href="/admin/settings/user_mailman_register?sync_all=1">'.t('Synchronize all user subscriptions').'</a>';
+
+  $sync_list = isset($_GET["sync_all"]) ? $_GET["sync_all"] : '';
+  if (is_numeric($sync_list)) {
+	  ini_set("max_execution_time", "0");
+	  $lists = _mailman_manager_get_lists();
+	  $sql = 'SELECT uid FROM {users} WHERE uid != 0;';
+	  $results = db_query($sql);
+	  while ($uid = db_result($results)) {
+		  $user = user_load($uid);
+		  foreach ($lists as $list) {
+		  	$subscription = _user_mailman_register_get_subscriptions($user, $list);
+		  }
+	  }
+  }
+
   return $output;
 }