From: Mail Delivery Subsystem <mailer-daemon@example.net>
To: sender@example.com
Subject: Delivery delayed
Date: Tue, 02 Jun 2026 10:05:00 +0000
Message-ID: <delayed@example.net>
Content-Type: text/plain; charset=utf-8

Delivery delayed. We will keep trying to deliver your message.
Final-Recipient: rfc822; waiting@example.com
Status: 4.4.1