Hello, I have configured SPF, DKIM, etc. on my server, also looked if the ip is not blacklisted, but still my emails always go to SPAM.

Here's the email headers that I get when I receive an email on Gmail (and goes to SPAM)

Delivered-To: receiver@gmail.com
Received: by 10.216.61.200 with SMTP id w50csp264314wec;
        Mon, 13 Oct 2014 14:27:48 -0700 (PDT)
X-Received: by 10.224.67.136 with SMTP id r8mr2327320qai.24.1413235668096;
        Mon, 13 Oct 2014 14:27:48 -0700 (PDT)
Return-Path: <sender@orbit83.com>
Received: from omega.orbit83.com (omega.orbit83.com. [107.170.182.30])
        by mx.google.com with ESMTPS id k62si26797330qge.88.2014.10.13.14.27.47
        for <receiver@gmail.com>
        (version=TLSv1.1 cipher=ECDHE-RSA-RC4-SHA bits=128/128);
        Mon, 13 Oct 2014 14:27:47 -0700 (PDT)
Received-SPF: pass (google.com: domain of sender@orbit83.com designates 107.170.182.30 as permitted sender) client-ip=107.170.182.30;
Authentication-Results: mx.google.com;
       spf=pass (google.com: domain of sender@orbit83.com designates 107.170.182.30 as permitted sender) smtp.mail=sender@orbit83.com;
       dkim=pass header.i=@orbit83.com
Received: from localhost (localhost [127.0.0.1])
    by omega.orbit83.com (Postfix) with ESMTP id E85A2121DD6
    for <receiver@gmail.com>; Mon, 13 Oct 2014 16:27:46 -0500 (CDT)
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=orbit83.com; s=mail;
    t=1413235666; bh=lL924zWkSc5qiwI4aQcsWA6PfpLi5xmPHL3UTl6rsr4=;
    h=From:Subject:Date:To:From;
    b=bZ4k6VDLYcAk6qQROANZ3bl0Nisz8lRCjn7DLK5evdx5SFikHN/Y5e/j5Y7GgqLiz
     WiGYj0kauOA18CHXEUj0wg9tye37mLu8txCJOEcqeTZlAbeKf1kmEGerjqicoYEl4K
     WJCYYM/0uLAUnmUDspvVlfKDaRpnsSdVc1vDt1w8=
X-Virus-Scanned: Debian amavisd-new at omega.orbit83.com
Authentication-Results: omega.orbit83.com (amavisd-new); dkim=pass
    header.i=@orbit83.com
Received: from omega.orbit83.com ([127.0.0.1])
    by localhost (omega.orbit83.com [127.0.0.1]) (amavisd-new, port 10024)
    with ESMTP id BBzEslitybO1 for <reciever@gmail.com>;
    Mon, 13 Oct 2014 16:27:33 -0500 (CDT)
Received: from [172.18.49.126] (unknown [200.52.77.210])
    by omega.orbit83.com (Postfix) with ESMTPSA id F1303121CB9
    for <reciever@gmail.com>; Mon, 13 Oct 2014 16:27:31 -0500 (CDT)
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=orbit83.com; s=mail;
    t=1413235653; bh=lL924zWkSc5qiwI4aQcsWA6PfpLi5xmPHL3UTl6rsr4=;
    h=From:Subject:Date:To:From;
    b=s7UVFFOfy7RXKoYlFNOyiFMwvPyTvGhqy5HECK5rM5fypskifXNL8EHVAaDVpeoV0
     Rpg0k8XLpOV2NUzHa5ILeKw+1HGdgZeGuIlTfcqacitrI2FeJOq+QyfjRZszLuwBiX
     9U9teX9en0WX7VKIZXWnS+Py0/Rdi8u7OJOzBp1A=
From: Agustin Ferrari <sender@orbit83.com>
Content-Type: multipart/alternative; boundary="Apple-Mail=_48B67ECC-742D-4C7E-91E9-C1982CB090AA"
Subject: q onda
Message-Id: <CD131220-E356-4AAB-843D-CD66EC4E4259@orbit83.com>
Date: Mon, 13 Oct 2014 16:27:29 -0500
To: reciever@gmail.com
Mime-Version: 1.0 (Mac OS X Mail 7.3 \(1878.6\))
X-Mailer: Apple Mail (2.1878.6)

don't know if I missing something, can any one help?

many thanks,