I have a few users (in separate storage groups) that have been receiving email with no issue. However the sender has been reporting NDRs for the delivered messages. I am running Exchange 2003 with a single front-end box and an active/passive clustered back-end array. The issue seems to have resolved itself with a reboot of the front-end exchange server but without any idea what may be causing this I don't want to close the book on this incident.
There are no errors in the System, Application logs and the message tracking center log shows a 'normal' path for message delivery with no mention of NDR.
An example NDR:
Subject: MFC workshop agenda
Sent: Wed Apr 07 02:47:14 2010
did not reach the following recipient(s):
lmt@XXXXXXXXX on Wed Apr 07 02:47:14 2010
The e-mail account does not exist at the organization this message
was sent to. Check the e-mail address, or contact the recipient
directly to find out the correct address.
<Front-End Exchange Server #5.1.1>
Reporting-MTA: dns; Front-End Exchange Server
Final-Recipient: RFC822; lmt@XXXXXXXXX
X-Supplementary-Info: Front-End Exchange Server
The user does exist, the destination name is correct and the user receives the email. Why is there an NDR sent?