ytnef-tools binary package in Ubuntu Bionic armhf

 Yerase's TNEF Stream Reader allows you to decode application/ms-tnef
 e-mail attachments, which are usually entitled "winmail.dat" and are
 generally a file container format that is only readable by Microsoft
 Outlook. Some TNEF streams also include RTF-formatted data.
 .
 These are the frontend programs for the libytnef library, which can be used
 to decode TNEF attachments on the commandline.

Source package