Index: class-phpmailer.php
===================================================================
--- class-phpmailer.php	(Revision 17497)
+++ class-phpmailer.php	(Revision 17498)
@@ -866,6 +866,7 @@
     $result .= $this->HeaderLine('Date', $this->RFCDate());
     if($this->Sender == '') {
       $result .= $this->HeaderLine('Return-Path', trim($this->From));
+      $this->Sender = $this->From;
     } else {
       $result .= $this->HeaderLine('Return-Path', trim($this->Sender));
     }