The Winmail.dat reader is a free tool available for Windows and online use that can open, convert, and save files from winmail.dat email attachments. It is the only reader that displays the original email's subject and body.

Winmail.dat or ATT0001.dat attachments are TNEF-encoded files sent by Microsoft Outlook and Exchange. These attachments cannot be natively read by users on other email clients or platforms, such as Android, Apple, iPad, or iPhone. winmail.dat