WinmailFileReader is a small yet quick letter opener to open and view winmail.dat files on Mac, it also enables you to preview every single attachment files in external applications or extract the files contained in winmail.dat attachment.

The winmail.dat file usually appears because various mail programs handle message formats differently. Certain messages sent from the Microsoft Outlook mail program (or a Microsoft Exchange server) may arrive with a winmail.dat attachment if your own mail program is not set up to handle mail in the Microsoft Outlook Rich Text Format. The winmail.dat file contains the Rich Text Format information for the message, but usually will not open normally. (These attachments are sometimes called T.N.E.F. files, short for Transport Neutral Encapsulation Format, which is the technical term for the format Outlook uses.)

Key Features of WinmailFileReader:
- Quickly to open and view winmail.dat file contents.
- Support open&preview every single attachment files in external application.
- Could help you extract and export all files contained in the winmail.dat attachment.
- Handy, small and easy to use.
- Fully support OS X 10.9 Mavericks.

What’s New

Version 3.0.0

1. Changed the app name and copyright info.
2. Other minor optimizations.

Ratings and Reviews

3.5 out of 5
10 Ratings

10 Ratings

MasonUIK9 ,

Small, Simple, does one thing well

The program opens a .dat file and displays the contents or attachments for me, it is almost instantaneous. Some of these files haunted me long time, but now it isn't difficult to get them opened and read. With this small app it is really easy to open files from Winmail.

Owen.Joyner ,

what I need

I usually receive some messages sent from the Microsoft Outlook which made me upset. After I downloaded this app, I no longer have to worry about this problem. It helped me to open and view winmail files quickly. It is really good!

Benmilson ,

Didn’t let me down. Thank you

I don’t know why, before the other WinmailViewer completely unable open .dat file. So, I search adn download the application - WInmailFileReader. It hepled me open all my cryptic winmail files. Your letter opener not let me down.


993.9 KB

OS X 10.6 or later, 64-bit processor



Age Rating


  • Family Sharing

    With Family Sharing set up, up to six family members can use this app.