Returned mail: Host unknown

[Mail Delivery Subsystem <MAILER-DAEMON@mordor.cs.du.edu>]

   ----- Transcript of session follows -----
550 pax.tpa.com.au (TCP)... 550 Host unknown
554 <mail-server@pax.tpa.com.au>... 550 Host unknown (Authoritative answer from name server)

   ----- Unsent message follows -----
Received: from nyx10.cs.du.edu by mordor.cs.du.edu with SMTP id AA26753
  (5.65c/IDA-1.4.4 for <mail-server@pax.tpa.com.au>); Fri, 5 Nov 1993 01:16:14 -0700
Received: by nyx10.cs.du.edu (4.1/SMI-4.1)
	id AA26238; Fri, 5 Nov 93 01:16:38 MST
Date: Fri, 5 Nov 93 01:16:38 MST
From: ateel@nyx10.cs.du.edu (A. J. Teel - Sui Juris)
Message-Id: <9311050816.AA26238@nyx10.cs.du.edu>
X-Disclaimer: Nyx is a public access Unix system run by the University
	of Denver.  The University has neither control over nor
	responsibility for the opinions or correct identity of users.
To: mail-server@pax.tpa.com.au
Subject: ...

send help
end
------------------------------------------------