From: "Bob" <bob@trusted.com>
To: me@example.com
Subject: Your Invoice #5
Date: Sat, 20 Jun 2026 10:00:00 +0000
Message-ID: <abc123@trusted.com>
MIME-Version: 1.0
Content-Type: multipart/mixed; boundary="BOUNDARY"

--BOUNDARY
Content-Type: text/plain; charset=utf-8

Hello, here is your invoice.
--BOUNDARY
Content-Type: text/plain; charset=utf-8
Content-Disposition: attachment; filename="invoice.txt"

LINE-ITEM 1: 100.00
--BOUNDARY--