I have Exchange 2010 with lots of messages stuck in the queue with the message:
451 4.4.0 Primary target IP address responded with: “421 4.2.1 Unable to connect.” Attempted failover to alternate host, but that did not succeed. Either there are no alternate hosts, or delivery failed to all alternate hosts.
all of those messages look to me like NDR for spam emails - here is and example:
Subject: Undeliverable: Your Whos Who Entry
Internet Message ID: <email@example.com>
From Address: <>
Size (KB): 7
Message Source Name: DSN
Source IP: 255.255.255.255
Date Received: 8/16/2012 12:01:58 PM
Expiration Time: 8/18/2012 12:01:58 PM
Queue ID: OURMAIL\188851
Should I be concerned about those? or just ignore them. Other email seems to be delivered fine.
Is there a way to disable NDR on the Exchange 2010 and is it a problem if I disable it?