diff -dur -x '*~' postfix-2.2.3.orig/src/master/master.c postfix-2.2.3/src/master/master.c
--- postfix-2.2.3.orig/src/master/master.c	2005-02-15 01:36:58.000000000 +0100
+++ postfix-2.2.3/src/master/master.c	2005-06-01 09:55:35.000000000 +0200
@@ -289,8 +289,8 @@
      * all MTA processes cleanly. Give up if we can't separate from our
      * parent process. We're not supposed to blow away the parent.
      */
-    if (debug_me == 0 && setsid() == -1)
-	msg_fatal("unable to set session and process group ID: %m");
+    if (debug_me == 0 && setsid() == -1 && getsid(0) != getpid())
+	msg_fatal("unable to set session and process group ID: %m (pid=%d, sid=%d)", (int)getpid(), (int)getsid(0));
 
     /*
      * Make some room for plumbing with file descriptors. XXX This breaks