What does this NDR mean?

[vic102482]

From: System Administrator
Sent: Wednesday, March 17, 2004 4:13 PM
To: Removed
Subject: Removed
Your message did not reach some or all of the intended recipients.

Subject: Removed
Sent: 3/17/2004 4:08 PM

The following recipient(s) could not be reached:

Remvoed on 3/17/2004 4:13 PM
The e-mail system was unable to deliver the message, but did not report a specific reason. Check the address and try again. If it still fails, contact your system administrator.
<EXCHANGE01.DOMAIN.COM #5.0.0 smtp;554 <coffman@deleted.net>: ****Relay access denied****>


Whats up with the relay access denied toward the bottom? I sent out like 100 emails and like 10 of them came back like this.

What could that be the result of?

 

[xmsre]

They use a mailer that allows them to specify the failure codes. 5.0.0 just means it's a permanent error. You could be on a blacklist, you could be failing reverse lookups, or this could be a server that uses a whitelist. About the only way to find out is to contact the administrator at the distant end.