From: sender@test.invalid
To: recipient@test.invalid
Subject: claims to be base64 but isn't
Message-ID: <not-really-base64@test.invalid>
Date: Fri, 18 Sep 2026 12:00:00 +0300
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: base64

notActuallyBase64 just plain text!