медленная доставка электронной почты, мягкое уведомление SPF

у нас есть сервер, который сохраняет и пересылает электронные письма на мою почту google ( = peter @ nowhow.be ).

Эти письма задерживаются, и, глядя на источник почты, я заметил эту spf softfail:

(google.com: домен перехода bounce-md_9656357.5757fa2a.v1-bc546ca56d9342cdabd5403911d98a8c@mandrillapp.com не определяет 176.31.117.132 в качестве разрешенного отправителя

Куда и что мне нужно адаптировать для решения этой проблемы? моя запись nowhow.be Google SPF?

Delivered-To: peter@nowhow.be
Received: by 10.55.51.2 with SMTP id z2csp2583562qkz;
        Wed, 8 Jun 2016 03:58:29 -0700 (PDT)
X-Received: by 10.25.216.27 with SMTP id p27mr3546145lfg.226.1465383509020;
        Wed, 08 Jun 2016 03:58:29 -0700 (PDT)
Return-Path: <bounce-md_9656357.5757fa2a.v1-bc546ca56d9342cdabd5403911d98a8c@mandrillapp.com>
Received: from tesla.mdware.org (ns395193.ip-176-31-117.eu. [176.31.117.132])
        by mx.google.com with ESMTPS id i129si345869lfe.139.2016.06.08.03.58.28
        for <peter@nowhow.be>
        (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128);
        Wed, 08 Jun 2016 03:58:28 -0700 (PDT)
Received-SPF: softfail (google.com: domain of transitioning bounce-md_9656357.5757fa2a.v1-bc546ca56d9342cdabd5403911d98a8c@mandrillapp.com does not designate 176.31.117.132 as permitted sender) client-ip=176.31.117.132;
Authentication-Results: mx.google.com;
       dkim=pass header.i=@mail4.mcsignup.com;
       dkim=pass header.i=@mandrillapp.com;
       spf=softfail (google.com: domain of transitioning bounce-md_9656357.5757fa2a.v1-bc546ca56d9342cdabd5403911d98a8c@mandrillapp.com does not designate 176.31.117.132 as permitted sender) smtp.mailfrom=bounce-md_9656357.5757fa2a.v1-bc546ca56d9342cdabd5403911d98a8c@mandrillapp.com;
       dmarc=fail (p=NONE dis=NONE) header.from=gmail.com
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    by tesla.mdware.org with esmtps (TLSv1.2:ECDHE-RSA-AES256-GCM-SHA384:256)
    (Exim 4.87)
    (envelope-from <bounce-md_9656357.5757fa2a.v1-bc546ca56d9342cdabd5403911d98a8c@mandrillapp.com>)
    id 1bAbBs-0002qh-Uf
    for info@textthebutler.be; Wed, 08 Jun 2016 12:58:29 +0200

DKIM-Signature: v=1; a=rsa-sha1; c=relaxed/relaxed; s=mandrill; d=mail4.mcsignup.com;
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Received: from pmta08.mandrill.prod.suw01.rsglab.com (127.0.0.1) by mail4.mcsignup.com id havt561jvmgh for <info@textthebutler.be>; Wed, 8 Jun 2016 10:57:46 +0000 (envelope-from <bounce-md_9656357.5757fa2a.v1-bc546ca56d9342cdabd5403911d98a8c@mandrillapp.com>)

DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=mandrillapp.com; 
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From: =?utf-8?Q?Filip?= <arborix.be@gmail.com>
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Date: Wed, 08 Jun 2016 10:57:46 +0000
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X-Get-Message-Sender-Via: tesla.mdware.org: redirect/forwarder owner info@textthebutler.be -> peter@nowhow.be
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