==== REQUIRED BASIC INFO OF YOUR IREDMAIL SERVER ====
- iRedMail version (check /etc/iredmail-release):
- Deployed with iRedMail Easy or the downloadable installer?
- Linux/BSD distribution name and version:
- Store mail accounts in which backend (LDAP/MySQL/PGSQL):
- Web server (Apache or Nginx):
- Manage mail accounts with iRedAdmin-Pro?
- [IMPORTANT] Related original log or error message is required if you're experiencing an issue.
====

Right now, the iRedMail is working all fine in term of sending and receving the mail but the mail sent to Gmail flagged as Spam.

I spent a week without any solution. I am using Amazon EC2 to host my mail server, I successfully setup DKIM, DMARC, SPF and even Reverse DNS. None of these solve the spam issue.

Any recommendation to solve this issue?

The below is mail showed in original sent to Gmail.

Delivered-To: xxxxxx@gmail.com
Received: by 2002:a1c:2397:0:0:0:0:0 with SMTP id j145csp1243744wmj;
        Thu, 17 Oct 2019 09:25:57 -0700 (PDT)
X-Google-Smtp-Source: APXvYqwtCZdOFKpiVJNMe9PEZU7/gIR4Iu3aU7tKuJRK1pnaAZNKCqkI0N0tjV2Fv7/8QMSooM/Y
X-Received: by 2002:a17:90a:8c86:: with SMTP id b6mr5474399pjo.129.1571329557475;
        Thu, 17 Oct 2019 09:25:57 -0700 (PDT)
ARC-Seal: i=1; a=rsa-sha256; t=1571329557; cv=none;
        d=google.com; s=arc-20160816;
        b=0B1wMUWc5qnTsXdmjmVXNW0Z2mkZOAjf/vyOdyFeIA7aigYbUnEYhJPRyQRw9km2Ch
         hJUwa6FZkP2rkne/9VJjuvBkFMhnq5kCCqLW0Om6zLG1OVFpD/G8ChsDstGCoVcD0ZJY
         pC/e9ewYUdzQ9nUqbGZKaVCO21JzFxmDJ4b/ASCBElEoZYt+p429XZESbj2EmVXVi9D7
         xlVvx/e1GI2DPsxwJdHanBphajE/EfetVXD1pQYL1Gy447yht0fitePrPco3KAbuVBo0
         Td75LzUDBNv+FMJMD4l+5KST39vqCredmmUWX/PaO/XAZPT3cV1qgSkgXCf9jWhT6RnC
         y/7Q==
ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816;
        h=user-agent:message-id:subject:to:from:date
         :content-transfer-encoding:mime-version:dkim-signature;
        bh=k59nXRXffycZghU81VHqG9SWGoeZQue8gC7tbC+0QFs=;
        b=uBTGFk+/2T5RHMsgrCmm5LK3GGq0u2xGlBtqFNNwPqaxJTVYYoIdezDfVhtIWolSt1
         mEWkn3zPpiCBidR520+wSEkNRrRPszOmf3jc25Vh+2NcLbozOId6jr6xbz3I6dgMC/gE
         TNw9makQ4lg/p5gzuLC87JYOwzin2d6qf7HyTQcTlkDT3/IBpW+/Zns+k6eZjLlnP1Rv
         9TBJ3OdyXy//knYyzUdB3ivLHyZ6FspjpUFAFU348i+X5E6f+00/eytkY+5HIho6P5BH
         bHASEd/iZhdbQ4W7fhZ0pUddQOIkcw28VAgFgL/xBfjmNdrOc39a6605/JsD9ASe27Ps
         QISQ==
ARC-Authentication-Results: i=1; mx.google.com;
       dkim=pass header.i=@lumhat.me header.s=dkim2 header.b=MqSfLqhw;
       spf=pass (google.com: domain of info@lumhat.me designates 18.140.221.35 as permitted sender) smtp.mailfrom=info@lumhat.me;
       dmarc=pass (p=QUARANTINE sp=QUARANTINE dis=NONE) header.from=lumhat.me
Return-Path: <info@lumhat.me>
Received: from mail.lumhat.me (mail.lumhat.me. [18.140.221.35])
        by mx.google.com with ESMTPS id c11si3029821pfr.14.2019.10.17.09.25.56
        for <xxxxxx@gmail.com>
        (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256);
        Thu, 17 Oct 2019 09:25:57 -0700 (PDT)
Received-SPF: pass (google.com: domain of info@lumhat.me designates 18.140.221.35 as permitted sender) client-ip=18.140.221.35;
Authentication-Results: mx.google.com;
       dkim=pass header.i=@lumhat.me header.s=dkim2 header.b=MqSfLqhw;
       spf=pass (google.com: domain of info@lumhat.me designates 18.140.221.35 as permitted sender) smtp.mailfrom=info@lumhat.me;
       dmarc=pass (p=QUARANTINE sp=QUARANTINE dis=NONE) header.from=lumhat.me
Received: from mail.lumhat.me (mail.lumhat.me [127.0.0.1])
    by mail.lumhat.me (Postfix) with ESMTP id 46vF036kzYz255n
    for <xxxxx@gmail.com>; Thu, 17 Oct 2019 16:25:55 +0000 (UTC)
Authentication-Results: mail.lumhat.me (amavisd-new); dkim=pass (1024-bit key)
    reason="pass (just generated, assumed good)" header.d=lumhat.me
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=lumhat.me; h=
    user-agent:message-id:subject:subject:to:from:from:date:date
    :content-transfer-encoding:content-type:content-type
    :mime-version; s=dkim2; t=1571329555; x=1573921556; bh=k59nXRXff
    ycZghU81VHqG9SWGoeZQue8gC7tbC+0QFs=; b=MqSfLqhwu22prn//9s+OzTreM
    5aEqwh7wivfjqMLXGTNGPRa0DjPNVB5Gi8AfQcRYTUBytPHo9WHuKA93r8YHyllC
    /mmmkMPoEq6tCQB0k1vLLvcu98E6OdNzg8hlvntsLG3L4oWAzJoht1YaM/SrJqO0
    /1U31c2vZYIbdo+qpY=
X-Virus-Scanned: Debian amavisd-new at mail.lumhat.me
Received: from mail.lumhat.me ([127.0.0.1])
    by mail.lumhat.me (mail.lumhat.me [127.0.0.1]) (amavisd-new, port 10026)
    with ESMTP id WsIuAu_94zpQ for <xxxxxx@gmail.com>;
    Thu, 17 Oct 2019 16:25:55 +0000 (UTC)
Received: from _ (mail.lumhat.me [127.0.0.1])
    by mail.lumhat.me (Postfix) with ESMTPSA id 46vF034WJcz24mZ
    for <xxxxx@gmail.com>; Thu, 17 Oct 2019 16:25:55 +0000 (UTC)
MIME-Version: 1.0
Content-Type: text/plain; charset=US-ASCII;
format=flowed
Content-Transfer-Encoding: 7bit
Date: Thu, 17 Oct 2019 23:25:55 +0700
From: info@lumhat.me
To: xxxxxx@gmail.com
Subject: hello
Message-ID: <f57265b2d103bbff2e81c7d9573fdd08@lumhat.me>
X-Sender: info@lumhat.me
User-Agent: Roundcube Webmail

hello there,

what are you doing?

I am doing good.

Thank you.

Best,

My iRedmail info:
- Deployed with downloable installer on Ubuntu
- Using Amazon EC2 to host
- iRedMail latest version
- Store mail account on PGSQL
- Webserver Ngix
- Managment mail account with iRedMail normal