Email spoofing issue

Posted on 2006-05-10
Medium Priority
Last Modified: 2009-02-05
We have an issue with someone apparently sending email to our internal users posing as our actual exchange server. Below is the header of an email. Note that the email looks like it is coming from our mail server (pti-nj.com) but the IP address ( is not ours. The email is sent with a from address of one of our internal users and sent to other users in our company. We have relay restrictions on our Exchange server (only allowing the IP address of our Exchange server to relay but does allow any authenticated user to relay), this is set on the Relay restrictions tab of the SMTP virtual server. HELP! We are getting a lot of these type of emails.

Microsoft Mail Internet Headers Version 2.0
Received: from pti-nj.com ([]) by mailserver.pti-nj.com with Microsoft SMTPSVC(5.0.2195.6713); Thu, 4 May 2006 08:12:34 -0400
X-MimeOLE: Produced By Microsoft Exchange V6.0.6603.0
From: <register@pti-nj.com>
To: <mktg@pti-nj.com>
Subject: Members Support
Date: Thu, 4 May 2006 19:11:47 +0700
MIME-Version: 1.0
Content-Type: multipart/mixed;
X-Priority: 3
X-MSMail-Priority: Normal
Return-Path: <register@pti-nj.com>
Message-ID: <MAILSERVERVY5jVkjA20000051a@mailserver.pti-nj.com>
X-OriginalArrivalTime: 04 May 2006 12:12:34.0818 (UTC) FILETIME=[06D57620:01C66F74]
Content-Type: text/html;
Content-Transfer-Encoding: 7bit
Content-Description: warning.htm
Content-Type: text/html;
Content-Transfer-Encoding: quoted-printable
Content-Disposition: attachment;




Question by:cberinger
1 Comment
LVL 31

Accepted Solution

LeeDerbyshire earned 2000 total points
ID: 16649230
It's not easy to stop this kind of thing.  Since they are using your own SMTP domain, it isn't technically relaying.  You could try enforcing SPF lookups (after creating your own SPF record, of course), but then you would without doubt lose many genuine emails.  I would be inclined to 'ride it out', and see if it stops.  If not, then a spam filter should stop most of the junk mail.  If you use E2003 SP2, then I find that the built-in IMF is quite good.  Mind you, many other people don't like it.

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