Hi everybody:
     I would appreciate someone`s help.  Since some days ago, every mail 
each user sends is returned to root, and also to the user that sent the 
message.  It appears something like this:
20 May 30 Mail Delivery Subsystem  (1,544) Returned mail: rewrite: map _at_ 
                                                                  not found
The mail arrives to it`s destination, but is is returned every time, and 
some times, several times.
This is an example of a returned mail that arrived to it`s destination:
********************************************************************
>From MAILER-DAEMON_at_xosfulsa.ulsa.mxFri May 31 05:37:59 1996
Date: Thu, 30 May 1996 06:00:27 -0600 (CST)
From: Mail Delivery Subsystem <MAILER-DAEMON_at_xosfulsa.ulsa.mx>
To: doa_at_xosfulsa.ulsa.mx, postmaster_at_xosfulsa.ulsa.mx
Subject: Returned mail: rewrite: map _at_ not found
Resent-Date: Fri, 31 May 1996 05:37:13 -0600 (CST)
Resent-From: system PRIVILEGED account <root_at_xosfulsa.ulsa.mx>
The original message was received at Thu, 30 May 1996 05:56:27 -0600 (CST)
from doa_at_localhost
   ----- Transcript of session follows -----
554 rewrite: map _at_ not found
   ----- Original message follows -----
Return-Path: <doa>
Received: by xosfulsa.ulsa.mx; id FAA03557; Thu, 30 May 1996 05:56:27 -0600 (CST)
Date: Thu, 30 May 1996 05:56:27 -0600 (CST)
From: Diana Ochoa Aduna <doa_at_xosfulsa.ulsa.mx>
To: raul_at_economista.com.mx
Subject: Saludos!!!!!
Message-ID: <Pine.OSF.3.91.960530055423.3549A-100000_at_xosfulsa.ulsa.mx>
MIME-Version: 1.0
Content-Type: TEXT/PLAIN; charset=US-ASCII
   ......MESSAGE......
****************************************************************************
Can somebody help me, please?
   Thanks....
                                         Mary Carmen
                                                (osf_at_xosfulsa.ulsa.mx)
Received on Fri May 31 1996 - 19:39:19 NZST