Hello i've been using zimbra for like 2 years now.

Suddenly some email accounts started being marked as spam when sending from outlook.

here are the headers

Code:
Return-Path: sender@domain.com
Received: from mail.domain.com (LHLO mail.domain.com) (192.168.169.33) by
 mail.domain.com with LMTP; Tue, 6 Apr 2010 11:18:30 -0400 (CLT)
Received: from localhost (localhost.localdomain [127.0.0.1])
	by mail.domain.com (Postfix) with ESMTP id B5B221F3800F
	for <reciever@domain.com>; Tue,  6 Apr 2010 11:18:30 -0400 (CLT)
X-Virus-Scanned: amavisd-new at mail.domain.com
X-Spam-Flag: YES
X-Spam-Score: 7.973
X-Spam-Level: *******
X-Spam-Status: Yes, score=7.973 tagged_above=-10 required=6.6
	tests=[AWL=-2.017, BAYES_80=2, DNS_FROM_OPENWHOIS=1.13,
	FH_DATE_PAST_20XX=3.188, HTML_MESSAGE=0.001, MIME_HTML_MOSTLY=0.001,
	RDNS_NONE=0.1, TVD_RCVD_SINGLE=1.351, TVD_SPACE_RATIO=2.219]
Received: from mail.domain.com ([127.0.0.1])
	by localhost (mail.domain.com [127.0.0.1]) (amavisd-new, port 10024)
	with ESMTP id ugfxW7d-22d1 for <reciever@domain.com>;
	Tue,  6 Apr 2010 11:18:30 -0400 (CLT)
Received: from JANTILAOCONTABILIDAD (unknown [192.168.169.143])
	by mail.domain.com (Postfix) with ESMTP id 4BBAC1F3800E
	for <reciever@domain.com>; Tue,  6 Apr 2010 11:18:30 -0400 (CLT)
From: "Susana Ceron" <sender@domain.com>
To: <reciever@domain.com>
Subject: prueba
Date: Tue, 6 Apr 2010 12:25:53 -0400
Message-ID: <000a01cad5a5$d4390ff0$7cab2fd0$@cl>
MIME-Version: 1.0
Content-Type: multipart/alternative;
	boundary="----=_NextPart_000_000B_01CAD584.4D276FF0"
X-Mailer: Microsoft Office Outlook 12.0
Thread-Index: AcrVpdQJUvO3FUTIS7C+agAKMEi7Ww==
Content-Language: es

This is a multi-part message in MIME format.

------=_NextPart_000_000B_01CAD584.4D276FF0
Content-Type: text/plain;
	charset="us-ascii"
Content-Transfer-Encoding: 7bit

prueba


------=_NextPart_000_000B_01CAD584.4D276FF0
Content-Type: text/html;
	charset="us-ascii"
Content-Transfer-Encoding: quoted-printable

<html xmlns:v=3D"urn:schemas-microsoft-com:vml" =
xmlns:o=3D"urn:schemas-microsoft-com:office:office" =
xmlns:w=3D"urn:schemas-microsoft-com:office:word" =
xmlns:m=3D"http://schemas.microsoft.com/office/2004/12/omml" =
xmlns=3D"http://www.w3.org/TR/REC-html40">

<head>
<meta http-equiv=3DContent-Type content=3D"text/html; =
charset=3Dus-ascii">
<meta name=3DGenerator content=3D"Microsoft Word 12 (filtered medium)">
<style>
<!--
 /* Font Definitions */
 @font-face
	{font-family:Calibri;
	panose-1:2 15 5 2 2 2 4 3 2 4;}
 /* Style Definitions */
 p.MsoNormal, li.MsoNormal, div.MsoNormal
	{margin:0cm;
	margin-bottom:.0001pt;
	font-size:11.0pt;
	font-family:"Calibri","sans-serif";}
a:link, span.MsoHyperlink
	{mso-style-priority:99;
	color:blue;
	text-decoration:underline;}
a:visited, span.MsoHyperlinkFollowed
	{mso-style-priority:99;
	color:purple;
	text-decoration:underline;}
span.EstiloCorreo17
	{mso-style-type:personal-compose;
	font-family:"Calibri","sans-serif";
	color:windowtext;}
.MsoChpDefault
	{mso-style-type:export-only;}
@page Section1
	{size:612.0pt 792.0pt;
	margin:70.85pt 3.0cm 70.85pt 3.0cm;}
div.Section1
	{page:Section1;}
-->
</style>
<!--[if gte mso 9]><xml>
 <o:shapedefaults v:ext=3D"edit" spidmax=3D"1026" />
</xml><![endif]--><!--[if gte mso 9]><xml>
 <o:shapelayout v:ext=3D"edit">
  <o:idmap v:ext=3D"edit" data=3D"1" />
 </o:shapelayout></xml><![endif]-->
</head>

<body lang=3DES link=3Dblue vlink=3Dpurple>

<div class=3DSection1>

<p class=3DMsoNormal>prueba<o:p></o:p></p>

</div>

</body>

</html>

------=_NextPart_000_000B_01CAD584.4D276FF0--
I need help urgently