Wrong email headers causing my emails to be blocked as spam?

[sashagal]

Hi,

Emails sent from my server are being blocked as spam, I'm worried that this is due to not having the right headers. Below are the headers from a blocked email. I am using postfix to send email, my site is mywebsite.com and the name of the machine hosting my site is server123.onlinehome-server.com. I would really appreciate any help with this! Let me know if there is any other information I can give that would be helpful. Thank you.

Headers
Received: from exmf003-5.intermedia.net ([127.0.0.1]) by localhost
(exmf003-5.intermedia.net [127.0.0.1]) (amavisd-new, port 10024) with ESMTP
id KS9HpZOG21YF for <xx@mail.com>; Mon, 6 Sep 2010
18:43:29 -0700 (PDT)
Received: from mywebsite.com (mywebsite.com
[74.99.99.99]) (using TLSv1 with cipher ADH-AES256-SHA (256/256 bits)) (No
client certificate requested) by exmf003-5.intermedia.net (Postfix) with
ESMTP id CF5381C106 for <xx@mail.com>; Mon, 6 Sep 2010
18:43:29 -0700 (PDT)
Received: from mywebsite.com (unknown [127.0.0.1]) by
mywebsite.com (Postfix) with ESMTP id 2A2E01ED41840; Tue, 7
Sep 2010 01:43:29 +0000 (UTC)
Received: from server123.onlinehome-server.com (unknown [127.0.0.1]) by
mywebsite.com (Postfix) with ESMTP; Tue, 7 Sep 2010 01:43:29
+0000 (UTC)
Date: Mon, 6 Sep 2010 20:43:29 -0500
From: My Website <system@mywebsite.com>
Reply-To: My Website <system@mywebsite.com>
To: "XX" <xx@mail..com>
CC: "XX" <xx@mail..com>
Message-ID: <1286835351.70.1283823809065.JavaMail.tomcat@serve r123.onlinehome-server.com>
Subject: New Site Request
MIME-Version: 1.0
Content-Type: multipart/mixed;
boundary="----=_Part_67_1393168417.1283823809043"
Return-Path: system@mywebsite.com

[till]

Is your server connected to the internet trough a dynamic IP?

[sashagal]

Hi,

I have a static IP, and this is the only website hosted on the machine (a virtual server). My /etc/hosts file includes my machine name: server123.onlinehome-server.com, but not the website name: mywebsite.com.

[falko]

Please check if your server is blacklisted: http://mxtoolbox.com/blacklists.aspx