--- common.php.orig	2009-10-20 23:25:20.000000000 +0400
+++ common.php	2015-04-19 10:22:35.000000000 +0300
@@ -18,6 +18,7 @@
  */
 
 if(!defined('POSTFIXADMIN')) { # already defined if called from setup.php
+    session_cache_limiter("nocache");
     session_start();
     define('POSTFIXADMIN', 1); # checked in included files
 }