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I have a postfix + dovecot mail server. The mails sent from this server to gmail goes in spam. The postfix is configured on our server and it has never been used for spamming. And i also added SPF, DKIM, PTR records for mail server. Here is my message:

Delivered-To: rfsiu0211@gmail.com
Received: by with SMTP id 31csp634153qgh;
        Wed, 30 Aug 2017 02:51:19 -0700 (PDT)
X-Received: by with SMTP id e77mr982568pfj.81.1504086679398;
        Wed, 30 Aug 2017 02:51:19 -0700 (PDT)
ARC-Seal: i=1; a=rsa-sha256; t=1504086679; cv=none;
        d=google.com; s=arc-20160816;
ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816;
ARC-Authentication-Results: i=1; mx.google.com;
       dkim=pass header.i=@chungtoi.com header.s=mail header.b=EACm4P8M;
       spf=pass (google.com: domain of thubd@chungtoi.com designates as permitted sender) smtp.mailfrom=thubd@chungtoi.com
Return-Path: <thubd@chungtoi.com>
Received: from mail.chungtoi.com (mail.chungtoi.com. [])
        by mx.google.com with ESMTPS id p64si4027806pga.272.2017.
        for <rfsiu0211@gmail.com>
        (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128);
        Wed, 30 Aug 2017 02:51:19 -0700 (PDT)
Received-SPF: pass (google.com: domain of thubd@chungtoi.com designates as permitted sender) client-ip=;
Authentication-Results: mx.google.com;
       dkim=pass header.i=@chungtoi.com header.s=mail header.b=EACm4P8M;
       spf=pass (google.com: domain of thubd@chungtoi.com designates as permitted sender) smtp.mailfrom=thubd@chungtoi.com
Received: from akai.home (unknown []) (Authenticated sender: thubd@chungtoi.com) by mail.chungtoi.com (Postfix) with ESMTPSA id 8001B12CFF0B for <rfsiu0211@gmail.com>; Wed, 30 Aug 2017 16:51:21 +0700 (ICT)
DKIM-Filter: OpenDKIM Filter v2.11.0 mail.chungtoi.com 8001B12CFF0B
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chungtoi.com; s=mail; t=1504086681; bh=tuhOtE9qjqASd8ZqCLUVOhKViWPHByzhGrNam6uFrTI=; h=To:From:Subject:Date:From; b=EACm4P8MjbGaoYbktN+dJu0cm1PCSIUKOv8wEcg8b0ZG/p/zF8JVfxXRIN49xGI+8
To: "Thư Bùi" <rfsiu0211@gmail.com>
From: Thu Bui <thubd@chungtoi.com>
Subject: Cập nhật bản ghi
Message-ID: <8e6af3e4-6ff6-3e3a-d022-9394d72486e9@chungtoi.com>
Date: Wed, 30 Aug 2017 16:51:17 +0700
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.1.0
MIME-Version: 1.0
Content-Type: text/plain; charset=utf-8; format=flowed
Content-Transfer-Encoding: 8bit
Content-Language: en-US

Các bạn nhận được thì gửi lại thông tin cho mình nhé!

As you can see, my mail server is set up with the following:

- The server has DKIM
- The server has a verified signed certificate
- SPF(TXT) is set correctly
- The server's PTR (reverse DNS) points correctly to my mail server
- All possible checking tools give a maximum result for the server (it should be trusted by everyone)

Does anyone know what the reason could be or what steps I should take?

marked as duplicate by Jenny D, Ward, mdpc, womble Sep 7 '17 at 1:35

This question has been asked before and already has an answer. If those answers do not fully address your question, please ask a new question.

  • Answers here may extend the dupe candidate by specifically gmail-related informations. – peterh Aug 31 '17 at 14:01

It seems that IP address of your mail server is blacklisted by some of RBL systems.

Check here and start removal process from each blacklisted RBL. Also you can check this one.

  • thanks for your answer! But it seems not be the main problem. My mailserver IP address is blacklisted by some RBL systems (like RatsDyna) which Gmail doesn't use to scoring. – Bui Thu Aug 31 '17 at 3:43

Have you tried sending an email with more and personalized content? I seem to recall that gmail treats short mails like yours often as spam, even if nothing else seems wrong with the setup.

According to the help page regarding spam in gmail:

Gmail automatically identifies spam and suspicious emails and marks those emails as spam. When you open your Spam label, you'll see any emails that were marked as spam by you or Gmail. Each email will include a label at the top that explains why it was sent to Spam.

So you should see a reason like this at the top of a mail in the spam folder, if that's the case:

Why is this message in Spam? It's similar to messages that have been detected by our spam filters. Learn more

Otherwise you may also see a message like this if the specific content of your message triggered the spam filter:

Why is this message in Spam? It contains content that's typically used in spam messages Learn more

  • I've tried sending personalized content emails, but they've still been treated like spam – Bui Thu Aug 31 '17 at 6:22
  • what does gmail say, why your messages are in spam? – Stefan Aug 31 '17 at 8:06
  • They said “ It's similar to messages that were detected by our spam filters.” – Bui Thu Aug 31 '17 at 9:39

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