Since Monday a.m., all mail to all [log in to unmask] has been bouncing.
I've attempted to mail a cognizant administrator at a related host about this.

Pete Weiss at Penn State

------------------------------ Message in error
-------------------------------
Received: from PSUVM (NJE origin SMTP@PSUVM) by PSUVM.PSU.EDU (LMail
          V1.2c/1.8c) with BSMTP id 0084; Tue, 4 Nov 1997 10:22:06 -0500
Received: from mail.hvcc.edu by PSUVM.PSU.EDU (IBM VM SMTP V2R2) with TCP;
   Tue, 04 Nov 97 10:22:05 EST
Received: from psuvm.psu.edu by mail.hvcc.edu with SMTP (AIX 4.1/UCB
 5.64/25-eef)
          id AA29998; Tue, 4 Nov 1997 08:02:34 -0500
Date: Tue, 4 Nov 1997 10:25:35 -0500
From: Mail Delivery Subsystem <[log in to unmask]>
Message-Id: <[log in to unmask]>
Subject: Returned mail: Host unknown
To: <[log in to unmask]>

   ----- Transcript of session follows -----
421 office.tcp... Deferred: Invalid argument
550 xxxxxxx@office,plunkdav@office... Host unknown: Invalid argument

   ----- Unsent message follows -----
Received: from psuvm.psu.edu by mail.hvcc.edu with SMTP (AIX 4.1/UCB
 5.64/25-eef)
          id AA25122; Tue, 4 Nov 1997 10:25:33 -0500
Message-Id: <[log in to unmask]>