Help to configure SPAM e-mails

Hi,

I have a Server with Linux/Cpanel, i have configure email to forward in the same server (user@domain.com > user2@domain.com) some times the user2@domain.com receive the email marked user@domain.com as spam.

How i can prevend if i'm sending email localy not marked as spam, also why is marked as spam where i can find the issue to be corrected.

 

Here the header i not see anything wrong.

Code:

Return-path: <user2@domain.com>
Envelope-to: user1@domain.com
Delivery-date: Thu, 18 Sep 2014 09:09:35 -0600
Received: from 1.1.1.1 ([1.1.1.1]:49356 helo=user2)
	by yui.myserver.com with esmtpa (Exim 4.82)
	(envelope-from <user2@domain.com>)
	id 1XUdKw-0002SQ-Qh
	for user1@domain.com; Thu, 18 Sep 2014 09:09:35 -0600
From: <user2@domain.com>
To: <user1@domain.com>
Subject: RV: Subject
Date: Thu, 18 Sep 2014 09:21:24 -0600
Message-ID: <000601cfd354$361fefd0$a25fcf70$@net>
MIME-Version: 1.0
Content-Type: multipart/alternative;
	boundary="----=_NextPart_000_0007_01CFD321.EB857FD0"
X-Mailer: Microsoft Office Outlook 12.0
Thread-Index: Ac/TUibfDmk+hm9uR76RknSDRo2AzQAAfvMQ
Content-Language: es-sv

Code:

Return-path: <user2@domain.com>
Envelope-to: user1@domain.com
Delivery-date: Fri, 26 Sep 2014 09:56:54 -0600
Received: from 1.1.1.1 ([1.1.1.1]:49254 helo=user2)
	by yui.myserver.com with esmtpa (Exim 4.82)
	(envelope-from <user2@domain.com>)
	id 1XXXt3-0007gI-Te; Fri, 26 Sep 2014 09:56:54 -0600
From: <user2@domain.com>
To: <user1@domain.com>
Cc: <user3@domain.com>
Subject: RV: Subject
Date: Fri, 26 Sep 2014 10:08:48 -0600
Message-ID: <000301cfd9a4$287cb880$79762980$@net>
MIME-Version: 1.0
Content-Type: multipart/mixed;
	boundary="----=_NextPart_000_0004_01CFD971.DDE24880"
X-Mailer: Microsoft Office Outlook 12.0
Thread-Index: Ac/YJ3jb6Gi/s3klQGegzXCSYwSWYwADkypwAAB0GHAAABy1wAAuku4wACxvclA=
Content-Language: es-sv

Code:

Return-path: <user2@domain.com>
Envelope-to: user1@domain.com
Delivery-date: Thu, 25 Sep 2014 14:36:29 -0600
Received: from 1.1.1.1 ([1.1.1.1]:50063 helo=user2)
	by yui.myserver.com with esmtpa (Exim 4.82)
	(envelope-from <user2@domain.com>)
	id 1XXFm9-0000Sf-9v; Thu, 25 Sep 2014 14:36:29 -0600
From: <user2@domain.com>
To: <user1@domain.com>
Cc: <user3@domain.com>
Subject: RV: Subject
Date: Thu, 25 Sep 2014 14:48:29 -0600
Message-ID: <003401cfd902$1113dc70$333b9550$@net>
MIME-Version: 1.0
Content-Type: multipart/alternative;
	boundary="----=_NextPart_000_0035_01CFD8CF.C6796C70"
X-Mailer: Microsoft Office Outlook 12.0
Thread-Index: Ac/Y/XuorlBpCTV1Qba64gBxIktKNAABEadAAAAQ/hA=
Content-Language: es-sv