Qmail: Improperly Delivered Bounces

[theywill]

Hi there,

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PRODUCT, VERSION, MICROUPDATE, OPERATING SYSTEM, ARCHITECTURE
CentOS 5.10 64-bit, Plesk 11.5.30 Update #47

PROBLEM DESCRIPTION

I'm using smtproutes to relay email to another email server. However, the receiving server rejects some messages. These end up back in my mail queue, often undeliverable because the messages are spam sent from a bogus address.

Occasionally, the bounce-bounce messages for these are delivered to a user address, but this user has nothing to do with the message loop.

1) Message is received
2) Message is rejected by server ABC (the server to which email is relayed)
3) A bounce cannot be delivered to the original *sending* (bogus) domain.
4) The bounce of that bounce is delivered to an unsuspecting user with an error about an email he/she actually sent.

Here's the first part...

-------------------------------------------------------------------------------------
Hi. This is the qmail-send program at mercury.hidden.net.
I'm afraid I wasn't able to deliver your message to the following addresses.
This is a permanent error; I've given up. Sorry it didn't work out.

<omohammed@cybsol.com>:
74.125.193.26 does not like recipient.
Remote host said: 550-5.1.1 The email account that you tried to reach does not exist. Please try
550-5.1.1 double-checking the recipient's email address for typos or
550-5.1.1 unnecessary spaces. Learn more at
550 5.1.1 http://support.google.com/mail/bin/answer.py?answer=6596 j4si1467319igu.42 - gsmtp
Giving up on 74.125.193.26.

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So here you see the bounce generated from the rejection by server ABC is attempted to be delivered to cybsol.com, but that's a bogus address. So the bounce bounces.

The crazy part is as follows. The bounce has information from an actual email sent by the user that receives the bounce message, but his message was delivered and it has nothing to do with omohammed@cybsol.com, which was a spam message sent to another domain.

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

Return-Path: <address@domain.com>
Received: (qmail 16119 invoked from network); 26 Aug 2014 06:52:28 -0500
Received: from host-xxx-xxx-xxx-xxx.har.xxx.net (HELO domain.com) (xxx.xxx.xxx.xxx)
by mercury.hidden.net with SMTP; 26 Aug 2014 06:52:27 -0500
Received: from BDWEB2 ([xxx.xxx.xxx.xxx]) by domain.com with Microsoft SMTPSVC(6.0.3790.4675);
Tue, 26 Aug 2014 07:58:07 -0400
X-MSMail-Priority: -1
X-Mailer: Mail Daemon (c)2010 by D.G. Gillilan
Thread-Topic: Daily Invoices for 8/25/2014 - 13291
thread-index: Ac/BJP/UIHWErWoYTWufOYH7HbKBUA==
Reply-To: <user@domain.com>
From: <user@domain.com>
To: <customer@customerdomain.COM>
Subject: Daily Invoices for 8/25/2014 - 13291
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STEPS TO REPRODUCE

Run mail mail server with qmail.

ACTUAL RESULT

EXPECTED RESULT

I would expect the bounce bounce to die a lonely death, not be delivered to an unrelated user with an error message about a message that user sent, which was actually delivered properly.

ANY ADDITIONAL INFORMATION
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Any ideas?

Thanks for your help in advance.

Best regards,
James