ktnef 4:4.12.0-0ubuntu1 (arm64 binary) in ubuntu trusty

 The TNEF File Viewer allows to handle easily mail attachments using the TNEF
 format. Those attachments are usually found in mails coming from Microsoft
 mail servers and embed the mail properties as well as the actual attachments.
 .
 An attachment in TNEF format is most often named winmail.dat or win.dat.
 .
 This package is part of the KDE PIM module.