can't receive mail from a certain domain, why?

microsoft.public.exchange.misc

7 Nov 2005 6:09 PM

rickster

My company is running exchange 5.5 with internet mail service. We have a
customer that gets this undeliverable message when they try to send us mail.

Reporting-MTA: dns; mailrtr3.mailzone.edeltacom.com
Arrival-Date: Thu, 3 Nov 2005 16:57:10 -0500 (EST)

Final-Recipient: RFC822; p**@domain.com
Action: failed
Status: 5.1.2
Remote-MTA: DNS; mailserver.domain.com
Last-Attempt-Date: Thu, 3 Nov 2005 16:57:30 -0500 (EST)

Other parts of the error message says 'host not found' and 'unknown host'.
The recipiant's email address is valid and receives other internet mail. Our
customer can't send mail to any of the hosts in our domain. Their IT person
doesn't know why they can't send us email, they're not having trouble sending
mail to other domains. I'm not blocking any domains on my end and I'm
receiving other internet mail. Any clues to what's going on or how to find
out what's going on?