Создал smtp-сервер. Проверьте, пожалуйста, служебные заголовки письма?

Код письма - оригинал.
Return-path:
Authentication-Results: mxs.mail.ru; spf=pass (mx131.mail.ru: domain of korsa5.ru designates 62.76.188.100 as permitted sender) smtp.mailfrom=nikiforov@korsa5.ru smtp.helo=korsa5.ru;
dkim=pass header.i=korsa5.ru
Received-SPF: pass (mx131.mail.ru: domain of korsa5.ru designates 62.76.188.100 as permitted sender) client-ip=62.76.188.100; envelope-from=nikiforov@korsa5.ru; helo=korsa5.ru;
Received: from [62.76.188.100] (port=34840 helo=korsa5.ru)
by mx131.mail.ru with esmtp (envelope-from )
id 1XeHdC-00016z-Do
for oai002@mail.ru; Wed, 15 Oct 2014 10:00:20 +0400
X-Mru-BL: 0:0:0
X-Mru-PTR: korsa5.ru
X-Mru-NR: 1
X-Mru-OF: Linux (Ethernet or modem)
X-Mru-RC: RU
DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=korsa5.ru; s=mail;
h=Content-Transfer-Encoding:Content-Type:Subject:To:MIME-Version:From:Date:Message-ID; bh=Vyqa2fJuaqGppG4RPCmJ1pwL6Op7YvW2l+9d0sXzDZo=;
b=huMTWIDyiOXrApxE73X7chfy0YoVcowWRNnNo25Ds65wOZ6Iso0hbQn6EEUBn2VYDGTgtc4VmYIS6RRMzk2H7ouy/5mYDeBINK+hvay7Hw54t5drYo5wdnWsSURGwpTqIWPUcuVxOZ/QaYzcN4Bx2mtznhlNmyGy2OC2S3164b8=;
Received: from 95-83-47-198.saransk.ru ([95.83.47.198] helo=[127.0.0.1])
by korsa5.ru with esmtpsa (UNKNOWN:AES128-SHA:128)
(Exim 4.72)
(envelope-from )
id 1XeHdA-0001FM-Ec
for oai002@mail.ru; Wed, 15 Oct 2014 06:00:16 +0000
Message-ID: <543E0D68.2080204@korsa5.ru>
Date: Wed, 15 Oct 2014 10:00:08 +0400
From: =?UTF-8?B?0JDQu9C10LrRgdC10Lk=?=
User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:31.0) Gecko/20100101 Thunderbird/31.1.2
MIME-Version: 1.0
To: oai002@mail.ru
Subject: =?UTF-8?B?0L/QvtC30LLQvtC90Lg=?=
Content-Type: text/plain; charset=utf-8; format=flowed
Content-Transfer-Encoding: quoted-printable
X-Antivirus: avast! (VPS 141014-1, 15.10.2014), Outbound message
X-Antivirus-Status: Clean
X-DMARC-Policy: none
X-DMARC-Result: pass
X-Mras: Ok
X-Mru-AVCheck: false
X-Mru-Authenticated-Sender: nikiforov@korsa5.ru
X-Spam: undefined

Рекомендую воспользоваться этим тестером, а так еще можно добавить текстовую версию письма.