tnef - 1.4.12-1.2+deb10u1 main

TNEF is a program for unpacking MIME attachments of type
"application/ms-tnef". This is typically a Microsoft only attachment.
.
The TNEF program allows one to unpack the attachments which were
encapsulated into the TNEF attachment, thus alleviating the need to use
Microsoft Outlook to view the attachment.