Index: branches/devel-vnext/index.php
===================================================================
--- branches/devel-vnext/index.php	(revision 664)
+++ branches/devel-vnext/index.php	(revision 689)
@@ -230,4 +230,10 @@
 // end session
 else if (($_task=='logout' || $_action=='logout') && isset($_SESSION['user_id'])) {
+    $CONFIG = $registry->get('CONFIG', 'core');
+    if (isset($CONFIG['external_logout']) && empty($CONFIG['external_logout']) === false) {
+        rc_main::rcmail_kill_session();
+        header('Location:' . $CONFIG['external_logout']);
+        exit;
+    }
     $OUTPUT->show_message('loggedout');
     rc_main::rcmail_kill_session();