diff --git a/DOCUMENTS/BACKUP_MX.txt b/DOCUMENTS/BACKUP_MX.txt
index b2deb95b..6f50dbea 100644
--- a/DOCUMENTS/BACKUP_MX.txt
+++ b/DOCUMENTS/BACKUP_MX.txt
@@ -5,20 +5,15 @@
 # Licensed under GPL for more info check GPL-LICENSE.TXT
 #
 
-REQUIRED!!
-----------
-- You are using Postfix 2.0 or higher.
-- You are using Apache 1.3.27 / Lighttpd 1.3.15 or higher.
-- You are using PHP 4.1 or higher.
-- You are using MySQL 3.23 or higher.
-
-
-READ THIS FIRST!
-----------------
-When this is an upgrade from Postfix Admin 1.5.4 please read UPGRADE.TXT!!
-
-More information is available on http://high5.net/howto/
+Please follow these steps if your mailserver is used as a backup MX for some
+(or all) of your domains.
 
+Note: The setup described in this file only checks the domain, not the full
+mail address. 
+You should use "reject_unverified_recipient" in your postfix config or setup
+"relay_recipient_maps" with a list of valid mail adresses on the primary mx
+to avoid that your backup MX accepts mails for non-existing recipient adresses.
+Without this, your backup MX might become a backscatter source.
 
 1. Modify main.cf
 -----------------
diff --git a/DOCUMENTS/UPGRADE.txt b/DOCUMENTS/UPGRADE.txt
index d1b1768f..0707b8f1 100644
--- a/DOCUMENTS/UPGRADE.txt
+++ b/DOCUMENTS/UPGRADE.txt
@@ -9,7 +9,7 @@ REQUIRED!!
 ----------
 - You are using Postfix 2.0 or higher.
 - You are using Apache 1.3.27 / Lighttpd 1.3.15 or higher.
-- You are using PHP 4.1 or higher.
+- You are using PHP 5.1.2 or higher.
 - You are using MySQL 3.23 or higher OR PostgreSQL v7.4+
 
 
diff --git a/INSTALL.TXT b/INSTALL.TXT
index 49b3c2a8..2f65e223 100644
--- a/INSTALL.TXT
+++ b/INSTALL.TXT
@@ -9,7 +9,7 @@ REQUIRED!!
 ----------
 - You are using Postfix 2.0 or higher.
 - You are using Apache 1.3.27 / Lighttpd 1.3.15 or higher.
-- You are using PHP 5.X 
+- You are using PHP 5.1.2 or higher.
 - You are using MySQL 3.23 or higher (5.x recommended) OR PostgreSQL 7.4 (or higher)