From: Attacker <bad@example.org>
Subject: Hostile attachment name
Date: Sat, 01 Aug 2026 10:00:00 +0000
Message-ID: <evil-1@example.org>
MIME-Version: 1.0
Content-Type: multipart/mixed; boundary="EVIL"

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

body
--EVIL
Content-Type: text/plain; name="../../../../tmp/pwned.txt"
Content-Disposition: attachment; filename="../../../../tmp/pwned.txt"

owned
--EVIL--