I tried looking around for a solution for this but have been unable to.
We have a new (1 month old) single-server installation of Exchange 2013 CU5, running on server 2012. It's in coexistence with an Exchange 2007 box. All users, groups, and everything have been migrated, we actually just shut down 2007 today. However, Exchange 2013 never seems to give accurate or helpful NDRs.
When someone sends an email to, let's say, a user who has left the company, so their mailbox is gone, the user who sent the email will receive an NDR. However, the NDR will not tell you the user who the email failed to. It shows the sender's account and says "command not allowed". This happens only to internal recipients. When sending to an external domain, we receive the NDR from the other domain with the explanation that the user does not exist or whatever. But within our domain, we never get a "helpful" NDR. It's just "command not allowed" and the email doesn't get to ANY of the recipients that it was sent to. Any ideas or help would be greatly appreciated!
Delivery has failed to these recipients or groups:
user1@ourdomain.com 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 email from certain senders, or another restriction may be preventing delivery.
Diagnostic information for administrators:
Generating server: mailserver.ourdomain
user1@ourdomain.com Remote Server returned '550 5.7.1 Command not allowed'
Original message headers:
Received: from mailserver.ourdomain ([removed]) by mailserver.ourdomain ([removed]) with mapi id 15.00.0913.011; Thu, 17 Jul 2014 10:18:03 -0500 MIME-Version: 1.0 Content-Type: text/plain Date: Thu, 17 Jul 2014 10:18:03 -0500 Message-ID: <removed > Subject: RE: ASAP