libkf5tnef-dev 4:17.08.3-0ubuntu1 (s390x binary) in ubuntu bionic

 Ktnef is a library for handling data in the TNEF format (Transport Neutral
 Encapsulation Format, a proprietary format of e-mail attachment used by
 Microsoft Outlook and Microsoft Exchange Server). The API permits access
 to the actual attachments, the message properties (TNEF/MAPI), and allows
 one to view/extract message formatted text in Rich Text Format.
 .
 This package contains the development files.