From: weird@example.com
To: mcptest@local
Subject: Kaputtes Encoding XUNKNOWNTOKEN
Date: Wed, 10 Jan 2018 12:00:00 +0100
Content-Type: text/plain; charset="x-unknown"
Content-Transfer-Encoding: 8bit

Koerpertext mit kaputtem Charset XUNKNOWNTOKEN und Umlaut ü.