Index: includes/common.inc
===================================================================
RCS file: /cvs/drupal/drupal/includes/common.inc,v
retrieving revision 1.611.2.5
diff -u -r1.611.2.5 common.inc
--- includes/common.inc	4 May 2007 08:56:30 -0000	1.611.2.5
+++ includes/common.inc	16 May 2007 01:03:07 -0000
@@ -1971,12 +1971,27 @@
     foreach ($headers as $name => $value) {
       $mimeheaders[] = $name .': '. mime_header_encode($value);
     }
-    return mail(
-      $to,
-      mime_header_encode($subject),
-      str_replace("\r", '', $body),
-      join("\n", $mimeheaders)
-    );
+    // Specify the envelope Return-Path address in the additional_parameters
+    // of mail() to overwrite the server's default Return-Path address
+    $return_path = mime_header_encode($headers['Return-Path']);
+
+    if ($return_path && !ini_get('safe_mode')) {
+      return mail(
+        $to,
+        mime_header_encode($subject),
+        str_replace("\r", '', $body),
+        join("\n", $mimeheaders),
+        '-f'. $return_path
+      );
+    }
+    else {
+      return mail(
+        $to,
+        mime_header_encode($subject),
+        str_replace("\r", '', $body),
+        join("\n", $mimeheaders)
+      );
+    }
   }
 }