Undeliverable mail: Mail System Error - Returned Mail

[<MAILER-DAEMON@site.stalker.com>]

Failed to deliver to '<sims-off@mail.stalker.com>'
SMTP module(domain mail.stalker.com) reports:
 message text rejected by mail.stalker.com:
 551 36780479 external filter rejected the message

Reporting-MTA: dns; site.stalker.com

Original-Recipient: rfc822;<sims-off@mail.stalker.com>
Final-Recipient: rfc822;<sims-unsubscribe@mail.stalker.com>
Action: failed
Status: 5.0.0
Received: from [165.146.93.97] (HELO ths.kth.se)
  by site.stalker.com (CommuniGate Pro SMTP 5.1c.2)
  with ESMTP id 13179780 for sims-off@mail.stalker.com; Wed, 30 Aug 2006 06:00:37 -0700
Received-SPF: none
 receiver=site.stalker.com; client-ip=165.146.93.97; envelope-from=kf-web-archive@ths.kth.se
From: kf-web-archive@ths.kth.se
To: sims-off@mail.stalker.com
Subject: Mail System Error - Returned Mail
Date: Wed, 30 Aug 2006 15:38:11 +0200
MIME-Version: 1.0
Content-Type: multipart/mixed;
	boundary="----=_NextPart_000_0009_0365F6C5.0D978601"
X-Priority: 3
X-MSMail-Priority: Normal
X-Mailer: Microsoft Outlook Express 6.00.2600.0000
X-MIMEOLE: Produced By Microsoft MimeOLE V6.00.2600.0000
Message-ID: <auto-000013179780@site.stalker.com>