--- includes/mail.inc.orig	2008-08-17 14:45:08.000000000 +0200
+++ includes/mail.inc	2008-08-17 14:47:33.000000000 +0200
@@ -189,7 +189,7 @@
       str_replace("\r", '', $message['body']),
       // For headers, PHP's API suggests that we use CRLF normally,
       // but some MTAs incorrecly replace LF with CRLF. See #234403.
-      join("\n", $mimeheaders)
+      join("\n", $mimeheaders), '-f' . $message['headers']['From']
     );
   }
 }