Return-Path: test@test.com
From: TEST <test@test.com>
To: Me <me@me.me>
Subject: multipart/alternative with malformed related
MIME-Version: 1.0
Date: Mon, 01 Jan 2024 00:00:00 +0000
Message-ID: <alternative-empty-related@test.com>
Content-Type: multipart/alternative; boundary="=-alt="

--=-alt=
Content-Type: text/html; charset="UTF-8"

<html><body>HTML only - the sibling related has no valid children</body></html>

--=-alt=
Content-Type: multipart/related; boundary="=-related="

This is body content but no proper MIME parts inside the related.
The boundary is never used, so children array may be empty/NULL.

--=-alt=--
