NDR issue - getting non-deliverable of random e-mail to my inbox after smarthost changeover

I cut over to a different smarthost (went from Symantec to Proofpoint) and noticed that I'm getting a non-delivery report e-mail in my Outlook inbox about every 20 mins. Most of them are regarding the same exact e-mail.

I've no idea how to track this down  far as why it's being triggered and why I am receiving it.

Can anyone assist? I'm trying to search via the proofpoint appliance search, as well as Exchange, and while I can see the messages there, it doesn't give me any insight as to why I'm getting a non-deliverable -- i'm not even a recipient.
At best I'm guessing I'm just being forwarded the e-mail via the smarthost appliance, but it doesn't help me much...

E-mail is:

From: Mail Delivery Subsystem [MAILER-DAEMON@ProofPointServer.localdomain.com]
Sent: Monday, November 02, 2015 3:05 PM
To: AWatch@server01.localdomain.com
Subject: Undeliverable: AMICAS Watch red alert for AMICAS Server #1873 (server02).

Delivery has failed to these recipients or groups:
AWatch@server01.localdomain.com
The recipient's e-mail address isn't correct. Please check the e-mail address and try to resend the message. If the problem continues, contact your helpdesk.
The following organization rejected your message: server01.localdomain.com.






Diagnostic information for administrators:
Generating server: ProofPointServer.localdomain.com
AWatch@server01.localdomain.com
server01.localdomain.com #<server01.localdomain.com #5.1.2 SMTP; 550 Host unknown> #SMTP#
Original message headers:
Return-Path: <>
Received: from pps.filterd (ProofPointServer.localdomain.com [127.0.0.1])
by
 ProofPointServer.localdomain.com (8.15.0.59/8.15.0.59) with SMTP id tA2Kw6sL042234
for
 <AWatch@server01.localdomain.com>; Mon, 2 Nov 2015 15:01:59 -0600
Received: from mail9.localdomain.com (mail9.localdomain.com [10.13.70.59])
by
 ProofPointServer.localdomain.com with ESMTP id 1xvts2gcwq-1
(version=TLSv1/SSLv3
 cipher=AES128-SHA bits=128 verify=NOT)  for <AWatch@server01.localdomain.com>; Mon,
 02 Nov 2015 15:01:59 -0600
MIME-Version: 1.0
From: <postmaster@externaldomain.com>
To: <AWatch@server01.localdomain.com>
Date: Mon, 2 Nov 2015 15:01:59 -0600
Content-Type: multipart/report; report-type=delivery-status;
boundary="8757241e-cd89-4947-a3ac-267b9be17f9d"
Content-Language: en-US
Message-ID: <f64df61d-7e36-4088-9418-10c36b0aea25@externaldomain.com>
In-Reply-To: <16471729.1446498118818.JavaMail.dicom@server02>
References: <16471729.1446498118818.JavaMail.dicom@server02>
Subject: Undeliverable: AMICAS Watch red alert for AMICAS Server #1873
 (server02).
X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:,, definitions=2015-11-02_12:,,
 signatures=0
X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 kscore.is_bulkscore=0
 kscore.compositescore=1 compositescore=0.9 ndrscore=0 suspectscore=3
 malwarescore=0 phishscore=0 bulkscore=0 kscore.is_spamscore=0 rbsscore=0.9
 spamscore=0 urlsuspectscore=0.9 adjustscore=0 adultscore=0 classifier=spam
 adjust=0 reason=mlx scancount=1 engine=8.0.1-1507310000
 definitions=main-1511020362
X-Regulatory-Partner: 1