TNEFView can read/extract the any information from tnef-file created in MS Outlook.
You may read the message with all mail information (subject, body, recipients, attachments etc)
If you have not the installed MS Outlook, you may recover this information from your tnef-file and copy/save in another format.
For example, extract all attachments from mail and save with original file.

This application don't use any external libraries and you may run this tool on computer without any additional setup/install.