diff -urN src.orig/spool_mbox.c src/spool_mbox.c
--- src.orig/spool_mbox.c	Wed Jan 16 11:56:55 2008
+++ src/spool_mbox.c	Mon Nov 16 09:32:16 2009
@@ -69,7 +69,8 @@
     temp_string = expand_string(
       US"From ${if def:return_path{$return_path}{MAILER-DAEMON}} ${tod_bsdinbox}\n"
       "${if def:sender_address{X-Envelope-From: <${sender_address}>\n}}"
-      "${if def:recipients{X-Envelope-To: ${recipients}\n}}");
+      "${if def:received_for{X-Envelope-To: <${received_for}>\n}"
+      "{${if def:recipients{${if match{${recipients}}{\\N.*[, ]\\N}{}{X-Envelope-To: <${recipients}>\n}}}}}}");
 
     if (temp_string != NULL) {
       i = fwrite(temp_string, Ustrlen(temp_string), 1, mbox_file);