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Mails not reaching from some domains to our exchange

Mails are not reaching from some domains to our exchange, please find the below bounce massage..

The original message was received at Mon, 21 Jul 2008 06:09:51 -0400 (EDT)
from imo-d21.mail.aol.com []


Your e-mail is being returned to you because there was a problem with its
delivery.  The address which was undeliverable is listed in the section
labeled: "----- The following addresses had permanent fatal errors -----".

The reason your mail is being returned to you is listed in the section
labeled: "----- Transcript of Session Follows -----".

The line beginning with "<<<" describes the specific reason your e-mail could
not be delivered.  The next line contains a second error message which is a
general translation for other e-mail servers.

Please direct further questions regarding this message to the e-mail
administrator or Postmaster at that destination.

--AOL Postmaster

   ----- The following addresses had permanent fatal errors -----

   ----- Transcript of session follows -----
451 4.4.1 reply: read error from vtpplexch.vtppl.com.
<pxavier@velankanigroup.com>... Deferred: Connection timed out with
Message could not be delivered for 3 hours
Message will be deleted from queue

Final-Recipient: RFC822; pxavier@velankanigroup.com
Action: failed
Status: 4.4.7
Last-Attempt-Date: Mon, 21 Jul 2008 09:14:47 -0400 (EDT)

Received: from  imo-d21.mx.aol.com (imo-d21.mail.aol.com []) by
imr-m06.mx.aol.com (v107.10) with ESMTP id RELAYIN5-64884606f3ac; Mon, 21 Jul
2008 06:09:51 -0400
Received: from patbj21@aol.in
    by imo-d21.mx.aol.com (mail_out_v38_r9.4.) id u.bdd.31e6c697 (37071)
     for <pxavier@velankanigroup.com>; Mon, 21 Jul 2008 05:52:29 -0400 (EDT)
Received: from mta-cen-v09.sim.aol.com (mta-cen-v09.sim.aol.com [])
by cia-db05.mx.aol.com (v121.5) with ESMTP id MAILCIADB055-90cf48845c5b36c; Mon,
21 Jul 2008 05:52:28 -0400
Received: from web-cen-v09 (web-cen-v09.sim.aol.com [])
    by mta-cen-v09.sim.aol.com (Postfix) with ESMTP id C40CC8BC58
    for <pxavier@velankanigroup.com>; Mon, 21 Jul 2008 05:52:16 -0400 (EDT)
References: <219E30562358DA4B84FC83E369007CF550D66C@vtpplexch.VTPPL.COM>
To: pxavier@velankanigroup.com
Subject: Re: test
Date: Mon, 21 Jul 2008 05:53:01 -0400
In-Reply-To: <219E30562358DA4B84FC83E369007CF550D66C@vtpplexch.VTPPL.COM>
X-MB-Message-Source: WebUI
MIME-Version: 1.0
From: patbj21@aol.in
X-MB-Message-Type: User
Content-Type: multipart/alternative;
X-Mailer: AOL Webmail 37563-STANDARD
Received: from by web-cen-v09.sim.aol.com ( with
HTTP (WebMailUI); Mon, 21 Jul 2008 05:53:01 -0400
Message-Id: <8CAB92EB277F3F0-14B8-41AE@web-cen-v09.sim.aol.com>

where pxavier@velankanigroup.com is from our exchange server vtpplexch.vtppl.com and mail was send from patbj21@aol.in

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Last Comment
Nitin Gupta
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Nitin Gupta
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A 4.4.7 NDR message usually indicates a problem on the receiving server; check the validity of the recipient's address. You can also perform an MX lookup on the receiving domain to determine if the receiving server is configured to receive messages correctly.

A 4.4.7 NDR message can also indicate that a message header limit has been reached on a remote server or that some other protocol timeout has occurred while communicating with the remote server. It may be necessary to reduce the number of recipients in the header of the message for the host to which you are receiving this error. If you then resend the message, it is placed in the queue again, and if the receiving server is up, the message is delivered.


A quick lookup in www.dnsstuff.com for your domain says that DNS config has 4 errors and your domain is blacklisted as well.
Get your ISP to create a Reverse DNS record for mailing purpose as you will have issues with sending to domains like AOL. It is a new measure to reduce spam.
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Nitin Gupta
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Great, you got to look at the report and goto to the RBL there you will find the details on how to unblock your Server.
Then you got to go ahead and secure it too.
As i can see from info you gave  the server of AOL that is trying to send mail have a private lan address.

>    imo-d21.mail.aol.com []

It is possible that your exchange is configured to refuse connections from private ip addresses for security and antispam.

This link will give you more info.

Try to examine exchange logs and try to disable
"Perform reverse DNS lookup on incoming messages"
option in exchange.

A firewall too can make the same thing, so if you are connected to internet through a firewall or antispam box the trouble can be there.
In exchange logs you will find the tracing of connection only if the firewall/antispam let pass the traffic from that AOL server.

Isn't 172.16 that comes in private range Point_In_Cyberspace?

it is from    172.16.x.x to    172.31.x.x     as stated in RFC

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Chris Dent
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> imo-d21.mail.aol.com []

That'll be the reporting MTA, don't worry about the internal IP of the reporting MTA. There's no way it can connect to the remote server (vtpplexch.vtppl.com) using that address, no matter how hard it tries.

It takes quite a while for me to connect to your SMTP service as well, far longer than it should. Approximately a minute before your Trend installation returns an SMTP banner.


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Dear All,

Thanks for quick response, issue is still there.. mails are passing through our SMTP server ( Trend Micro messaging security suite ) and reaching our exchange (vtpplexch.vtppl.com) and from there its getting bounce, PTR record is there for velankanigroup.com which is pointing to our SMTP server, I am getting 60% of mails but rest are bouncing back, for testing I send 10 test mail from AOL to my email (pxavier@velankanigroup.com) with 30 min gap 6 mails got delivered and 4 got bounce back.. So I think some issue with the exchange server.

Perform reverse DNS lookup on incoming messages is not enabled on our server (FYI)

Avatar of Nitin Gupta
Nitin Gupta
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  • Enable Reverse DNS.
  • Check your Firewall logs....
  • Check Trend Micro Logs...
  • Send the NDR details for those 4 maisl
In exchange logs you'll find some more info about message bounce.
Mybe you have to enable logging for the smtp.

Try to look if those 4 bounced mails came from the same server and the right six from another one ore the same of the four bounced.
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Chris Dent
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> and from there its getting bounce

What's the bounce message in that case? That doesn't match up with the situation detailed in the header in the original question.

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Nitin Gupta
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