Index: smtp.module
===================================================================
RCS file: /cvs/drupal-contrib/contributions/modules/smtp/smtp.module,v
retrieving revision 1.15.2.14
diff -u -F^f -r1.15.2.14 smtp.module
--- smtp.module	15 Jan 2008 23:11:30 -0000	1.15.2.14
+++ smtp.module	26 Feb 2008 19:18:45 -0000
@@ -201,7 +201,10 @@ function drupal_mail_wrapper($mailkey, $
       $mail->message_type = "pre";
     }
     else if (strtolower($key) == 'reply-to') {
-      $mail->AddReplyTo = $value;
+      // Only add a "reply-to" if it's not the same as "return-path".
+      if ($value != $header['Return-Path']) {
+        $mail->AddReplyTo($value);
+      }
     }
     else if (strtolower($key) == 'return-path') {
       if (trim($value) !=  '') {