Everyone receives Non Delivery Receipts (NDR's) when they send email (from an external email address) to a distribution group within a Server 2011 for Small Business Server organization.
This only happens when someone outside of the organization sends an email to this distribution group.
Whenever anyone emails this distribution group using an internal company email address, the emails go through without any problems.
What do I need to do to fix this issue?
Here is the NDR message (I have renamed the actual company and user names):
Delivery has failed to these recipients or groups:
Your message wasn't delivered due to a permission or security issue. It may have been rejected by a moderator, the address may only accept e-mail from certain senders, or another restriction may be preventing delivery.
Diagnostic information for administrators:
Generating server: company.com
#< #5.7.1 smtp;550 5.7.1 RESOLVER.RST.AuthRequired; authentication required> #SMTP#
Original message headers:
Received: from internalserver.mycompany.hosting (18.104.22.168) by
SBS.internal.companyname.local (192.168.234.150) with Microsoft SMTP
Server id 14.1.339.1; Thu, 13 Oct 2011 08:27:17 -0700
Received: from MAGCAEX01.mycompany.dom (192.168.2.131) by
magcaex02.mycompany.dom (192.168.2.196) with Microsoft SMTP Server (TLS)
id 22.214.171.124; Thu, 13 Oct 2011 08:27:45 -0700
Received: from MAGCAEX01.mycompany.dom ([fe80::7d66:824c:559:c54b]) by
MAGCAEX01.mycompany.dom ([fe80::7d66:824c:559:c54b%10]) with mapi; Thu, 13
Oct 2011 08:27:44 -0700
From: Mike Smith <email@example.com>
To: Report <Report@company.com>
Subject: RE: test-826
Date: Thu, 13 Oct 2011 15:27:14 +0000