Those can be one of 4 things:
1) Some spammer is sending the original messages and using your e-mail
address as the sender.
2) Someone else has a PC infected with a virus and the virus is sending
itself as the original message and using your e-mail address as the
sender.
3) The message is the virus itself, pretending to be a returned mail.
4) Your PC is infected with a virus and it has been sending itself. And
this is really a returned mail that your PC sent.

In cases 1, 2, and 3 above, the messages are not coming from your PC and
are not going through your e-mail account. There's nothing you can do
to prevent anyone from sending an e-mail with your e-mail address as the
From header, just as you can't prevent anyone from sending a postal mail
and putting your name and address as the return address. At this point
all you can do is filter out the messages. Your ISP may offer some
filtering at the mail server.

To make sure that case 4 above is not the cause, you should check your
PC with an updated anti-virus program.

From a quick look at the headers you supplied, it's most likely # 1.

--

Mike - http://pages.prodigy.net/michael_santovec/techhelp.htm



"Nightsky" wrote in message
...
I keep getting mail from a MAILER DAEMON that my message could not be
delivered.
The actual message displayed is in Spanish, and I never wrote or sent
such a message.
What can I do about this?

Here is the entire message and header:

X-Apparently-To: via 68.142.201.112; Fri, 05 Dec
2008 06:59:35 -0800
X-Originating-IP: [200.42.0.146]
Authentication-Results: mta122.sbc.mail.re3.yahoo.com
from=postino12.prima.com.ar; domainkeys=neutral (no sig)
Received: from 207.115.20.192 (EHLO flpi190.prodigy.net)
(207.115.20.192)
by mta122.sbc.mail.re3.yahoo.com with SMTP; Fri, 05 Dec 2008
06:59:33 -0800
X-Header-Overseas: Mail.from.Overseas.source.200.42.0.146
X-Originating-IP: [200.42.0.146]
Received: from postino12.prima.com.ar (postino12.prima.com.ar
[200.42.0.146])
by flpi190.prodigy.net (8.13.8 inb regex/8.13.8) with SMTP id
mB5ExVnM018151
for ; Fri, 5 Dec 2008 06:59:32 -0800
Message-Id:
Received: (qmail 3055 invoked for bounce); 5 Dec 2008 14:59:31 -0000
Date: 5 Dec 2008 14:59:31 -0000
From:
To:
MIME-Version: 1.0
Content-Type: multipart/mixed;
boundary="1228489171postino12.prima.com.ar1816855"
Subject: failure notice

--1228489171postino12.prima.com.ar1816855

(postino12.prima.com.ar)
Su mensaje no pudo ser entregado - Sua mensagem nao pode ser enviada -
Your message could not be delivered.

:
Esta casilla ha expirado por falta de uso.

--- Mensaje original adjunto.

--1228489171postino12.prima.com.ar1816855
Content-Type: message/rfc822

Return-Path:
Received: (qmail 3032 invoked from network); 5 Dec 2008 14:59:31 -0000
Received: from unknown (HELO 200.42.0.146) (24.232.42.44)
by postino12.prima.com.ar with SMTP; 5 Dec 2008 14:59:31 -0000
Received: from (HELO fl2o) [124.238.237.155] by 200.42.0.146 id
v5snGt9dS628; Fri, 05 Dec 2008 10:54:32 -0400
Message-ID: j5t1-z9d81601ashd4ab@gsrn71xclg1x7
From: ""
Reply-To: ""
To:
Subject: Compramos su casa, departamento, local, etc.
Date: Fri, 05 Dec 2008 10:54:32 -0400
X-Mailer: eGroups Message Poster
MIME-Version: 1.0
Content-Type: multipart/alternative;
boundary="D1EA_FD_._.0D_E7"
X-Priority: 3


--D1EA_FD_._.0D_E7
Content-Type: text/plain;
Content-Transfer-Encoding: quoted-printable

Compro su propiedad, pago en efectivo

Aproveche antes de que la crisis global se profundice para vender

Compro locales, oficinas, departamentos, casas, etc. solo en capital
feder=
al y gran buenos aires, interior abstenerse. En cualquier estado

Solo propiedades hasta US$100.000

Envienos en mail con el detalle de la propiedad que desea vender a
argenti=
incluyendo toda la informacion posible

No responda este mail ya que no sera leido

=20

--D1EA_FD_._.0D_E7--


--1228489171postino12.prima.com.ar1816855--