Received: from localhost.localdomain (unknown [xxx.xxx.xxx.xxx])
    (using TLSv1.2 with cipher xxx (256/256 bits))
    (No client certificate requested)
    by mail-tester.com (Postfix) with ESMTPS id xxx
    for <test-xxx@mail-tester.com>; Mon, 29 Apr 2019 18:35:18 +0200 (CEST)

Received: from localhost.localdomain (localhost [127.0.0.1])
    by localhost.localdomain (8.15.2/8.15.2/Debian-3) with ESMTP id xxx
    for <test-xxx@mail-tester.com>; Mon, 29 Apr 2019 17:35:18 +0100

Received: from mydomain.com (www-data@localhost)
    by localhost.localdomain (8.15.2/8.15.2/Submit) with SMTP id xxx
    for <test-xxx@mail-tester.com>; Mon, 29 Apr 2019 17:35:18 +0100