Sendmail & How to reject mail with executable attachments

Hello-
Recently I've been getting a lot of mail with attatchments "test.scr" and "appl.exe", a few of which have been identified as viruses. I'm wondering if there is any way to tell sendmail to reject any email containing an executable attatchment.

The following was returned from another machine, as my outlook has apparently delivered to my address book.

-->

This message was created automatically by mail delivery software.

A message that you sent could not be delivered to one or more of its
recipients. This is a permanent error. The following address(es) failed:

adam@thewatchdesk.com
This message has been rejected because it has
a potentially executable attachment "test.scr"
This form of attachment has been used by
recent viruses or other malware.
If you meant to send this file then please
package it up as a zip file and resend it.

------ This is a copy of the message, including all the headers. ------

Return-path: <jbruns@webdevsol.com>
Received: from [24.53.186.180] (helo=webdevsol.com)
by fhh.firehousehosting.com with esmtp (Exim 4.24)
id 1AlU4p-0004PI-BQ
for adam@thewatchdesk.com; Tue, 27 Jan 2004 09:20:27 -0500
From: jbruns@webdevsol.com
To: adam@thewatchdesk.com
Subject: Error
Date: Tue, 27 Jan 2004 09:18:59 -0500
MIME-Version: 1.0
Content-Type: multipart/mixed;
boundary="----=_NextPart_000_0006_70F4F082.659BE0AC"
X-Priority: 3
X-MSMail-Priority: Normal
Message-Id: <E1AlU4p-0004PI-BQ@fhh.firehousehosting.com>

This is a multi-part message in MIME format.

------=_NextPart_000_0006_70F4F082.659BE0AC
Content-Type: text/plain;
charset="Windows-1252"
Content-Transfer-Encoding: 7bit

The message contains Unicode characters and has been sent as a binary attachment.


------=_NextPart_000_0006_70F4F082.659BE0AC
Content-Type: application/octet-stream;
name="test.scr"
Content-Transfer-Encoding: base64
Content-Disposition: attachment;
filename="test.scr"

TVqQAAMAAAAEAAAA//8AALgAAAAAAAAAQAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA
AAAAqAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA
AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAUEUA
AEwBAwAAAAAAAAAAAAAAAADgAA8BCwEHAABQAAAAEAAAAGAAAGC+AAAAcAAAAMAAAAAASgAAEAAA
AAIAAAQAAAAAAAAABAAAAAAAAAAA0AAAABAAAAAAAAACAAAAAAAQAAAQAAAAABAAABAAAAAAAAAQ
AAAAAAAAAAAAAADowQAAMAEAAADAAADoAQAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA

I've no idea how to do it with sendmail, but it's trivial to do with qmail:
http://www.qmail.org/qmail-smtpd-viruscan-1.3.patch

Look into procmail for mail filtering.

Chris

I've installed the E-mail Sanitizer. It's an easy setup and the attachments are completely user configurable. Also, you can do a bit of AV filtering if you like.

The program can be found on

http://www.impsec.org/email-tools/p...l-security.html

It runs through an easy and basic procmail system.