Return-Path: <MAILER-DAEMON>
Date: Fri, 25 Aug 2017 21:25:34 +0000 (UTC)
From: MAILER-DAEMON (Mail Delivery System)
Subject: Undelivered Mail Returned to Sender
To: foo@example.com
Message-Id: <12345@foo.bar.mail>
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: quoted-printable

This is a mail with an invalid from header that can't be fixed.
It's missing the sender's email address.