--- guestbook.module.orig	2008-12-13 17:35:23.000000000 +0100
+++ guestbook.module	2008-12-13 17:35:34.000000000 +0100
@@ -528,7 +528,7 @@ function guestbook_form_entry_form_submi
 
   $from = variable_get('site_mail', ini_get('sendmail_from'));
   if ($iSendEmail) {
-    drupal_mail('guestbook_notification', $iSendEmail, 'New guestbook entry', $message, $from);
+    drupal_mail('guestbook_notification', $iSendEmail, t('New guestbook entry by @username', array('@username' => $user->uid == 0 ? $edit['anonname'] : $user->name)), $message, $from);
   }
 
   // Insert new message