Mail being tagged with uid

[Shahjehan Khatri <Shah@ASU.Edu>]

We're running Zmailer (Toronto version) on SunOS 4.1.3 on a SPARCstation 
10 (ecstest.asu.edu).

There are around 40 people logged on to machine.  When some of them send 
mail (using Pine), it gets tagged as being from "uid#XXXX@ecstest.asu.edu"  
Why would that be?  Lack of system resources?

What's more, mail sent to such an address is being delivered to the 
postmaster@ecstest.asu.edu , as illustrated below.

Will someone please tell me what's going on?

Thanks!

--

---------- Forwarded message ----------
Date: Sat, 9 Jul 1994 10:30:39 -0700
From: PMDF Mail Server <postmaster@asu.edu>
To: postmaster@asu.edu, uid#5067@ecstest.asu.edu
Subject: Undeliverable mail: SMTP delivery failure

The message could not be delivered to:

Addressee: bwalthe@nauproj.az.us
Reason: Illegal host/domain name found.