I am using zimbra 8 OS , its Antispamming engin and antivirus server dosn't detecting spam mails , as some one has send me email with attachment but inside attachment there is .exe but its icon is pdf. but why it dons't block ???

Return-Path: message@securebank.com
## Zimbra antispamer and antivirus dosn't work well ###
Received: from mail.mydomain.com (LHLO mail.mydomain.com) ( by
mail.mydomain.com with LMTP; Mon, 17 Dec 2012 20:27:41 +0500 (PKT)
Received: from localhost (localhost [])
by mail.mydomain.com (Postfix) with ESMTP id BA3221E0F8E
for <farrukhndm@mydomain.com>; Mon, 17 Dec 2012 20:27:41 +0500 (PKT)
X-Quarantine-ID: <1g8CClIN_LAd>
X-Virus-Scanned: amavisd-new at mydomain.com
X-Amavis-Alert: BAD HEADER SECTION, MIME error: error: unexpected end of
header; ; error: part did not end with expected boundary; ; error:
unexpected end of parts before epilogue
X-Spam-Flag: NO
X-Spam-Score: 1.623
X-Spam-Level: *
X-Spam-Status: No, score=1.623 tagged_above=-10 required=6.6

tests=[BAYES_50=0.8, RDNS_NONE=0.793, T_FSL_HELO_NON_FQDN_2=0.01,
Received: from mail.mydomain.com ([])
by localhost (mail.mydomain.com []) (amavisd-new, port 10024)
with ESMTP id 1g8CClIN_LAd for <farrukhndm@mydomain.com>;
Mon, 17 Dec 2012 20:27:36 +0500 (PKT)
Received: from securebank.com (unknown [])
by mail.mydomain.com (Postfix) with ESMTP id 1E4A31E0F87
for <farrukhndm@mydomain.com>; Mon, 17 Dec 2012 20:27:33 +0500 (PKT)
Received: from Fax.mydomain.com ( by mydomain.com ( with Microsoft SMTP Server (TLS) id F3HJKG1J; Mon, 17 Dec 2012 10:29:27 -0500
Received: from FaxServer.mydomain.com ( by SMTP.mydomain.com ( with Microsoft SMTP Server id OOH9SYDI; Mon, 17 Dec 2012 10:29:27 -0500
Date: Mon, 17 Dec 2012 10:29:27 -0500
From: Fax Server <Incoming.Fax@mydomain.com>
X-MS-Has-Attach: yes
X-MS-Exchange-Organization-SCL: -1
X-MS-TNEF-Correlator: <IRKFR69VL1GWNQID4ODQKQ1TJ4YRRUD3JFIN6D@mydomain.c om>
X-MS-Exchange-Organization-AuthSource: E32YRO39T5H8ME2@mydomain.com
X-MS-Exchange-Organization-AuthAs: Internal
X-MS-Exchange-Organization-AuthMechanism: 02
X-MS-Exchange-Organization-AVStamp-Mailbox: MSFTFF;7;0;0 0 0
X-Priority: 3 (Normal)
Message-ID: <FIYCXD2ILJGNEL9SDVSG8S65RKY255235BPAR9@mydomain.c om>
To: <farrukhndm@mydomain.com>
Subject: INCOMING FAX REPORT : Remote ID: 749-646-3665
MIME-Version: 1.0
Content-Type: multipart/mixed;

Content-Type: text/plain; charset=koi8-r
Content-Transfer-Encoding: 8bit

************************************************** *******
************************************************** *******

Date/Time: 11/09/2012 01:52:32 CST
Speed: 41291 bps
Connection time: 08:07
Pages: 9
Resolution: Normal
Remote ID: 749-646-3665
Line number: 749-646-3665
Description: 2013 Recruitment plan

************************************************** *******

Content-Type: application/zip; name="IncomingFax.zip"
Content-Transfer-Encoding: base64
Content-Disposition: attachment; filename="IncomingFax.zip"

## Google Anti spammer works fine ###
Send results from to Google account

This is the mail system at host mail.mycomain.com.

I'm sorry to have to inform you that your message could not
be delivered to one or more recipients. It's attached below.

For further assistance, please send mail to postmaster.

If you do so, please include this problem report. You can
delete your own text from the attached returned message.

The mail system

<fxxxxx@Gmail.com>: host aspmx.l.google.com[] said: 552-5.7.0
Our system detected an illegal attachment on your message. Please 552-5.7.0
visit Some file types are blocked - Gmail Help to 552 5.7.0
review our attachment guidelines. s1si3236456qct.56 (in reply to end of
DATA command)