This is regarding Exchange 2003 on a SBS 2003 server.
A little background on this issue is.
I can send to every domain except one, which is a different email server that I manage that is on a linux box. I get this error message in the Event viewer everytime I send a message to this domain.
Event Type: Error
Event Source: MSExchangeTransport
Event Category: NDR
Event ID: 3015
Time: 11:19:19 AM
A non-delivery report with a status code of 5.3.0 was generated for recipient rfc822;firstname.lastname@example.org
et (Message-ID <6BADCB664F403D4F9874873BC
Causes: Exchange mistakenly attempted mail delivery to an incorrect MTA route.
For more information, click http://www.microsoft.com/contentredirect.asp
Solution: Check your route and topology; use the winroute tool to ensure the routes are properly replicated between servers and routing groups.
The returned message I get in the user's email box is this:
Your message did not reach some or all of the intended recipients.
Sent: 6/12/2006 12:23 PM
The following recipient(s) could not be reached:
.net on 6/12/2006 12:23 PM
The message cannot be delivered due to a configuration error on the server. Please contact your Administrator.
<server.domain.local #5.3.0 smtp;553 5.3.0 <Administrator@sending domain.com>... No such user here>
Also in Exchange System Manager under Queues In the addition information part it says
"An SMTP protocol error occurred."
Any help would really be appreciated