Internet Headers?

By Drew Nicholson, dnicholson@OutlookExchange.com

Here's a question I got a few weeks ago. It centers around a misunderstanding of how information is transferred across the internet.

Do you know how I can stop the internet header being put on mails coming from our Exchange server. I would be very grateful if you could tell me how this is done.

If you go into outlook and then select view options and internet header you can see the ip address and the domain name of the machine. This is a security issue and we would like to turn it off so people on the outside of the company can not see the server where the email came from. Please see below; [Drew's note: all ip addresses and email names have been changed]

Received: from server.com (mail.server.com [10.0.0.1]) by server.com with SMTP (Microsoft Exchange Internet Mail Service Version 5.5.2650.21)
id HBSBPWS9; Fri, 16 Mar 2001 16:03:35 -0000
Received: from server.com ([10.0.0.1])
by server.com with esmtp (Exim 3.03 #1)
id 14dwkN-000CIa-00
for john.doe@email.com; Fri, 16 Mar 2001 16:06:36 +0000
Received: from computer [10.0.0.1] by server.com with ESMTP
(SMTPD32-6.05) id AA17ABD0084; Fri, 16 Mar 2001 11:06:47 -0500
From: "Drew Nicholson"
To: "John Doe"
Subject: RE: IMS
Date: Fri, 16 Mar 2001 10:03:11 -0600
Message-ID:
MIME-Version: 1.0
Content-Type: text/plain;
charset="iso-8859-1"
Content-Transfer-Encoding: 7bit
X-Priority: 3 (Normal)
X-MSMail-Priority: Normal
X-Mailer: Microsoft Outlook IMO, Build 9.0.2416 (9.0.2910.0)
X-MimeOLE: Produced By Microsoft MimeOLE V5.00.2919.6700
Importance: Normal
In-Reply-To: <5FDC792697F3D41186E3000629F7B59F01235F@UKLDNMX02>

I wrote: Unfortunately, this behaviour is by design, and necessary to the function of SMTP mail. Without knowing the domain name, and/or the IP address of at least the external firewall NIC, the server that receives the mail sent from your company has no way of knowing where it came from, or how to formulate the headers for a reply. I've pasted some of the headers from a mail from a friend of mine below -- he has a firewall, and the IP address you see is that IP address. If you use NATing, the system will show the NATed address, not the internal address.

What you need to do is set up a good firewall, lock down your exchange server so it's not a relay, and check things out every so often.

NAT stands for NETWORK ADDRESS TRANSLATION -- where a product, like a firewall, takes an internal IP address (like 196.168.2.10) and translates it into an external, routable IP address, like 208.206.50.4. Depending on the product, you may have to code this in manually, or simply set up the parameters in the GUI.

I'd suggest talking to a security consultant about that. I can give you some names, if you want...

Sorry I couldn't give you a better answer. However, since my friend is helping me out, I would request that you go to www.tiggercam.co.uk before you go and check out my articles again... :)

Thanks go out to the TS group for all their help!

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