Google Mail entdeckt Mails als Spam [Postfix]

Ich verwende einen ispconfig-Web- / Mail-Server und das Problem ist, dass meine E-Mails bei Google in Spam landen. Ich habe alles eingerichtet, rDNS, DKIM, SPF, dmarc, also denke ich nicht, dass der Rekordteil ein Problem wäre. Mein Mail-Header enthält jedoch an einer Stelle localhost, dass es eine sehr schlechte Praxis ist, wie ich hörte, weil Google es nicht mag.

Delivered-To: privateacc@gmail.com Received: by 2002:aed:2be7:0:0:0:0:0 with SMTP id e94-v6csp879456qtd; Tue, 26 Jun 2018 01:16:08 -0700 (PDT) X-Google-Smtp-Source: AAOMgpdMXb1sd9e8+CGZm5UWsGVGV2G5So66uCWqVsQCptMdhHxphnQj2iyCHqJgHJhujlVRGeaa X-Received: by 2002:a5d:4306:: with SMTP id h6-v6mr558073wrq.58.1530000968344; Tue, 26 Jun 2018 01:16:08 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1530000968; cv=none; d=google.com; s=arc-20160816; b=MhBt1s06ETIYsikSsJkpxi0hyr4cCgI/+/4zE+vMSzV4Su4SHqkjtE968b45v9aUHR 4F0OZZRwzm3BjPHBDjrg5FY55D49rQB+GUYwiNR6wmWRVx9Cjlfd9K3TpHMQlpWEx955 5FAJ4dlhNGmYAdzZ8XWiRacbfQrR7YWeQHAqqCx6TbOMQ4N9SUS4oWY9OyBZ6Vcdyp0K M/1uSFUldLSjauIzMCu6binU6BN5q/6TNIC03FxyWhRE0xowszA4LgJD4UqQD64fKEoA txZ1QjXC+OASiWfL1R2lQS/zCBwMUq3qjMtrBGDdVTmsQdG0bqt2rLUv4pjajDJiXIM7 U8fA== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=content-language:mime-version:user-agent:date:message-id:subject :from:to:dkim-signature:arc-authentication-results; bh=f87H22OjvOAW9flgprGZogNpubh4T1X8JmegL8h3LxM=; b=dcZMOGTjiaxxHwav6FRyqLnRkmtqakBEEGGO0W7uy3Uq9UGdGJ4/BRpjGLg4Y4qbvl df79X6i51neY/G6X7eVBoKpiTkF+fIAYbRNJNembCbmDJfR0m4J/Ba6lsH6DJRNzaOSV EjJrXA22d0rdtiqLWAUXfwzBLXzZ7Hsu49/B0DMCulk4+WMbCI+Jqw5/lCnS7DV5FA/q 9d9oMRPLWAvwc4/xPXsJWzgoYMyhQXYeGYFRDT+qM8P0eOf+tRDC3pkTT0JQL7f3uOLz SzjDH4ln3JjoN4WCwtC9aS332rpAmQuF/Q0qbztb3a4QRGQho1LYpzRkp0C5q6fowmY7 C+yw== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass header.i=@example.com header.s=default header.b=MLJoQ6mi; spf=pass (google.com: domain of company@example.com designates YY.YY.YYY.YYY as permitted sender) smtp.mailfrom=company@example.com; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=example.com Return-Path: <company@example.com> Received: from mail.example.com (mail.example.com. [YY.YY.YYY.YYY]) by mx.google.com with ESMTPS id h18-v6si1173503wrr.20.2018.06.26.01.16.08 for <privateacc@gmail.com> (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Tue, 26 Jun 2018 01:16:08 -0700 (PDT) Received-SPF: pass (google.com: domain of company@example.com designates YY.YY.YYY.YYY as permitted sender) client-ip=YY.YY.YYY.YYY; Authentication-Results: mx.google.com; dkim=pass header.i=@example.com header.s=default header.b=MLJoQ6mi; spf=pass (google.com: domain of company@example.com designates YY.YY.YYY.YYY as permitted sender) smtp.mailfrom=company@example.com; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=example.com Received: from localhost (localhost [127.0.0.1]) by mail.example.com (Postfix) with ESMTP id BC89B56406 for <privateacc@gmail.com>; Tue, 26 Jun 2018 10:16:07 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=example.com; h= content-language:content-type:content-type:mime-version :user-agent:date:date:message-id:subject:subject:from:from; s= default; t=1530000966; x=1531815367; bh=y3K031cw5dXuKH6FKdvt0KZN 8YuBBixONrHJK24NlAM=; b=MLJoQ6mipg+fjabDpidFG5ysG7zhKhKO7+uJm55S 4IFiYv5s3zPgj0VfH/RW0D3Z9+AjbxnZ5Ed7KrFmq3wjBGQCbhnBhvT/yAAIGaTq sgLe5xdiSyUzKOfSD7Zu/vbBt9KCvIjeufgiRhp3THEZeOgoA8aA4Ftw7wbvYpBc RT4= X-Virus-Scanned: Debian amavisd-new at mail.example.com Received: from mail.example.com ([127.0.0.1]) by localhost (mail.example.com [127.0.0.1]) (amavisd-new, port 10026) with ESMTP id rxAAFvmoEOV3 for <privateacc@gmail.com>; Tue, 26 Jun 2018 10:16:06 +0200 (CEST) Received: from [192.168.1.149] (unknown [XX.XXX.XXX.XXX]) (Authenticated sender: company@example.com) by mail.example.com (Postfix) with ESMTPSA id B46F75635F for <privateacc@gmail.com>; Tue, 26 Jun 2018 10:16:06 +0200 (CEST) To: privateacc@gmail.com From: Diogo Jesus <company@example.com> Subject: test Message-ID: <cc6d790a-8c7c-7751-6864-fe36962d9c1d@example.com> Date: Tue, 26 Jun 2018 10:16:04 +0200 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:52.0) Gecko/20100101 Thunderbird/52.8.0 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="------------E56F9C1A6EEA50EAF52DC248" Content-Language: fr X-Antivirus: Avast (VPS 180625-4, 25/06/2018), Outbound message X-Antivirus-Status: Clean  --------------E56F9C1A6EEA50EAF52DC248 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit  --------------E56F9C1A6EEA50EAF52DC248-- 

Meine Frage ist, warum sende ich immer noch E-Mails an Google Mail?