--- qmail-smtpd.c.orig	2005-07-13 12:42:16.998697299 +0200
+++ qmail-smtpd.c	2005-07-13 12:42:35.393412418 +0200
@@ -621,7 +621,9 @@
   }
 
   switch(mfcheck()) {
-    case DNS_HARD: err_hmf(); return;
+    case DNS_HARD:
+        strerr_warn4("qmail-smtpd: invalid envelope sender: <",addr.s,"> at ",remoteip,0);
+        err_hmf(); return;
     case DNS_SOFT: err_smf(); return;
     case DNS_MEM: die_nomem();
   }