why is this mail recognized as Junk?

[gunzer.andreas]

Hi guys,

i have a new Webaccess Email system. When I send mails to outlook
users these mails are recognized as Junk (automatically moved in "Junk
Mail" folder upon retrieval).

This is such a mail:

Return-Path: <[email protected]>
X-Flags: 0000
Delivered-To: GMX delivery to (e-mail address removed)
Received: (qmail invoked by alias); 03 Nov 2009 18:28:47 -0000
Received: from p54A3B275.dip.t-dialin.net (EHLO zarafa.domain.local)
[84.163.178.117]
by mail.gmx.net (mp015) with SMTP; 03 Nov 2009 19:28:47 +0100
X-Authenticated: #1026749
X-Provags-ID: V01U2FsdGVkX19YPtcOCp1YhqKDtAxT+PZe4k3I501V2+hp9QWfOm
EdIK0UHUQIuRhL
Subject: Here we go
From: =?windows-1252?Q?mein_Name?= <[email protected]>
To: (e-mail address removed)
Date: Tue, 3 Nov 2009 19:29:05 +0100
Mime-Version: 1.0
Content-Type: text/plain; charset=windows-1252
Content-Transfer-Encoding: quoted-printable
X-Priority: 3 (Normal)
X-Mailer: Zarafa 6.30.4-17264
Message-Id: <vmime.4af07671.15d8.740003b62cf3a1ba@zarafa-server>
X-FuHaFi: 0.00
X-GMX-Antivirus: 0 (no virus found)
X-GMX-Antispam: 0 (Mail was not recognized as spam);
Detail=5D7Q89H36p77e5KAPs1l6rP5fv
+zoqqtknv10KtVrra2GNW6hlNQtBFwF2r5dHKv1dQaM
Koh3LsXc/Db0kX9B0o9TKA/
gHa9cUFup0qzVgl887w9fk3rdv2oIdcJrUyqQ33l3MQsoPqsypfga
ZxPPw==V1;
X-GMX-UID: NjK6DbMaa2A6qIqLhXQys+MyOWhhakfi

 

[Diane Poremsky [MVP]]

How long is the message? Short messages are more likely to be tagged as spam
by the filter. Beyond that, its hard to say - its rarely anything you could
identify from the header.

--
Diane Poremsky [MVP - Outlook]

Outlook & Exchange Solutions Center: http://www.slipstick.com/

Outlook Tips by email:
mailto:[email protected]

EMO - a weekly newsletter about Outlook and Exchange:
mailto:[email protected]

 

[gunzer.andreas]

It seems that it does not depend on the length of the message.

Any other hints for me?