black list

in the last few days i keep getting mass mails for unkown users
which are not define inside qmail such as bill@... and alex@..
they have attached emails with zip file include a virus
how can I block them or avoid them from using my smtp
system is any black list to block such accounts
to drop their packets

Thanks



----- Original Message -----
From: <MAILER-DAEMON@sdcdomain.com>
To: <finence@sdcdomain.com>
Sent: Sunday, July 10, 2005 2:46 AM
Subject: failure notice


> Hi. This is the qmail-send program at sdcdomain.com.
> I'm afraid I wasn't able to deliver your message to the following
addresses.
> This is a permanent error; I've given up. Sorry it didn't work out.
>
> <bill@sdcdomain.com>:
> Sorry, no mailbox here by that name. vpopmail (#5.1.1)
>
> --- Below this line is a copy of the message.
>
> Return-Path: <finance@sdcdomain.com>
> Received: (qmail 80871 invoked from network); 10 Jul 2005 09:45:59
-0000
> Received: from unknown (HELO sdcdomain.com) (10.6.10.68)
> by ns1.sdcdomain.com with SMTP; 10 Jul 2005 09:45:59 -0000
> From: finance@sdcdomain.com
> To: bill@sdcdomain.com
> Subject: Hello
> Date: Sun, 10 Jul 2005 12:43:05 +0300
> MIME-Version: 1.0
> Content-Type: multipart/mixed;
> boundary="----=_NextPart_000_0002_0A666A7C.F976A610"
> X-Priority: 3
> X-MSMail-Priority: Normal
>
> This is a multi-part message in MIME format.
>
> ------=_NextPart_000_0002_0A666A7C.F976A610
> Content-Type: text/plain;
> charset="Windows-1252"
> Content-Transfer-Encoding: 7bit
>
> Here are your banks documents.
>
>
> ------=_NextPart_000_0002_0A666A7C.F976A610
> Content-Type: application/octet-stream;
> name="message.scr"
> Content-Transfer-Encoding: base64
> Content-Disposition: attachment;
> filename="message.scr"
>