From: Alice <alice@example.org>
To: Daniel <daniel@example.org>
Subject: referencing in-reply-to-loop-21
Message-ID: <mid-loop-12@example.org>
In-Reply-To: <mid-loop-21@example.org>
Date: Thu, 16 Jun 2016 22:14:41 -0400

Note Message-ID and In-Reply-To: in file in-reply-to-loop-21