email to gmail / outlook.com marked as spam

[bast...@gmail.com]

Hi,
I have an issue with mail sent from my server.
All emails sent to gmail or outlook.com accounts are marked as spam.
I checked and tried some configurations but I cannot find errors.
I have debian 8 with postfix dovecot, spamassassin.
Using mail-tester.com result is 10/10. And no issue on smtp server check by mxtoolbox.

Please see the following email detail with headers (just obfuscate ip and email address).

Please may you help me?
Many thanks

Delivered-To: mailf...@gmail.com
Received: by 10.13.239.3 with SMTP id y3csp1243726ywe;
Sat, 22 Apr 2017 09:19:30 -0700 (PDT)
X-Received: by 10.28.238.211 with SMTP id j80mr3531718wmi.97.1492877970228;
Sat, 22 Apr 2017 09:19:30 -0700 (PDT)
Return-Path: <mye...@mydomain.com>
Received: from mydomain.com (myserver.mydomain.com. [xxx.yyy.zzz.kkk])
by mx.google.com with ESMTPS id 63si7758017wml.91.2017.04.22.09.19.30
for <mailf...@gmail.com>
(version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128);
Sat, 22 Apr 2017 09:19:30 -0700 (PDT)
Received-SPF: pass (google.com: domain of mye...@mydomain.com designates xxx.yyy.zzz.kkk as permitted sender) client-ip=xxx.yyy.zzz.kkk;
Authentication-Results: mx.google.com;
dkim=pass header.i=@mydomain.com;
spf=pass (google.com: domain of mye...@mydomain.com designates xxx.yyy.zzz.kkk as permitted sender) smtp.mailfrom=mye...@mydomain.com;
dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=mydomain.com
Received: from [192.168.1.16] (unknown [88.147.41.141]) by mydomain.com (Postfix) with ESMTPSA id B356710200C for <mailf...@gmail.com>; Sat, 22 Apr 2017 18:19:29 +0200 (CEST)
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=mydomain.com; s=mail; t=1492877969; bh=j32uUvSIwjcdb+K5k6WfXC8Kn7YigY2AooZirbXA3NY=; h=From:Subject:Date:To:From; b=OWH9NgGHMo9WMMYCBx/5UaJ7hFkO2aiLqHspOuTlZt+O0aXzRcVS/f4mma7jR3U80
kUnU/jkXPQHkOPOASO56LBCje8xbuXT9XHp42oKt5KfWhmibs/nwMrlQDqDLA2itG8
VIrSVJphpXXyNV7fAk4s52l7f3i9IzI6EdiQSThw=
From: Name Surname <mye...@mydomain.com>
Content-Type: text/plain; charset=us-ascii
Content-Transfer-Encoding: 7bit
Subject: prova invio
Message-Id: <3BE25943-65AB-4C2C...@mydomain.com>
Date: Sat, 22 Apr 2017 18:19:28 +0200
To: Piccinini Lorenzo <mailf...@gmail.com>
Mime-Version: 1.0 (Mac OS X Mail 8.2 \(2104\))
X-Mailer: Apple Mail (2.2104)
X-Spam-Status: No, score=-1.0 required=3.0 tests=ALL_TRUSTED autolearn=ham autolearn_force=no version=3.4.0
X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on myserver

prova invio posta