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RDNS Failed on emails sent using a mail sender from client machines

Last Modified: 2012-02-21
We use exchange server 2003 to send our emails, and the same is configured to use a message labs as a smart host.

Emails are going fine when they are sent from outlook (connected to exchange server), however when we use a mailing software from client machines we get RDNS failed error on the emails.

Received: from web.domain.com ([] RDNS failed) by domain.com with Microsoft SMTPSVC(6.0.3790.4675); Mon, 13 Feb 2012 11:25:37 +0000
From: "Test User" <test.user@domain.com> "

And a bit about our DNS Settings,
our mail server internal ip is
external ip for the mail server has rdns as mail2.domain.com
Our browsing IP has RDNS as web.domain.com

How do i get the RDNS failed sorted with our settings as above??

Many thanks for your help
Watch Question

Is this actually causing you a problem, or do you just not like the message?  Put another way, are the mails failing to be delivered, or is this the only symptom?

The message appears because your client software is sending the emails to your exchange server over SMTP (as opposed to Outlook, which is creating the mails directly in Exchange).  Exchange will add a Received: header to the top of any email it receives over SMTP, and in that header says who it got the email from - your client machine in this case.  Presumably this client machine has the IP address  Exchange is trying to do a reverse lookup on this internal address, and is finding no PTR record for it.  If you want to fix the message therefore you will need to add a PTR record for this IP address into your *internal* DNS.  If it's already there, make sure that the Exchange server is configured to use the internal DNS server as its resolver.

This message will not of itself prevent the mail being delivered, so you can safely ignore it.  On the other hand if the mail is not being delivered, then you have some other issue as well, and I suggest you post further details of the symptoms.


thanks a lot bluebook,,
that was really informative..

We are getting few emails bounced back saying , emails rejected due to spam content. Can you suggest us a website or a link where we can check our smtp headers and see if there is an obvious issue. Here are some samples of error messages

This is the mail delivery agent at messagelabs.com.
I was not able to deliver your message to the following addresses.

xxx.187.xxx.30 failed after I sent the message.
Remote host said: 550 5.7.1 virus Sanesecurity.Jurlbl.Auto.66c4d51536866f15540d1d7005c779c3.UNOFFICIAL detected by ClamAV - http://www.clamav.net

--- Below this line is a copy of the message.

Return-Path: <justin@domain.com>
X-Env-Sender: justin@domain.com
X-Msg-Ref: server-11.tower-174.messagelabs.com!1329211486!13272696!3
X-Originating-IP: [xxx.204.xxx.75]
X-StarScan-Version: 6.5.5; banners=-,-,-
X-VirusChecked: Checked
Received: (qmail 13085 invoked from network); 14 Feb 2012 09:24:51 -0000
Received: from mail2.domain.com (HELO domain.com) (xxx.204.xxx.75)
  by server-11.tower-174.messagelabs.com with SMTP; 14 Feb 2012 09:24:51 -0000
thread-index: Aczq+cIbH8Z7ajQCQDaH22V63KHkTQ==
Received: from web.domain.com ([] RDNS failed) by domain.com with Microsoft SMTPSVC(6.0.3790.4675); Tue, 14 Feb 2012 09:19:28 +0000
Content-Class: urn:content-classes:message
Importance: normal
Priority: normal
X-MimeOLE: Produced By Microsoft MimeOLE V6.00.3790.4862
From: "domain" <justin@domain.com>
Subject: domain MARKET UPDATE...........tough love
To: "daniel" <daniel@wineco.com>
Content-Type: multipart/related;
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Date: Tue, 14 Feb 2012 09:19:28 +0000
Return-Path: <justin@domain.com>
Message-ID: <LIVESRV1kUwWpSWerOc00006060@domain.com>
X-OriginalArrivalTime: 14 Feb 2012 09:19:28.0546 (UTC) FILETIME=[C0922020:01CCEAF9]

This is a multi-part message in MIME format.

Content-Type: multipart/alternative;

Content-Type: text/plain;
Content-Transfer-Encoding: quoted-printable
This one is on us!
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Very detailed answer thanks for that

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