How to open winmail.dat files on Ubuntu and Debian Linux
The winmail.dat file is a container file format used by Microsoft Outlook to send attachments in richtext formatted emails. To open winmail.dat on Linux, use the tnef utility.
sudo apt-get install tnef
Open a shell window, navigate to the directory where the winmail.dat file is saved, then execute the command:
to extract all files that are stored in the winmail.dat into the current directory.