Open Winmail.dat, MSG and XPS files with just a double-click.

Try all in-app purchases 14 days for free!

A winmail.dat file is an email from Microsoft Outlook that can not be read by other email applications. It needs to be converted for the content to be accessible.

Letter Opener does that with a simple double-click!

With 10 years experience (and a special dislike for winmail.dat files) we made sure that working together with Microsoft Outlook and Windows users can be simple and seamless.

- Open winmail.dat and MSG files and convert Microsoft Outlook appointments, notes, contacts etc. to macOS native formats.

- Convert Microsoft XPS documents to Adobe PDF files

- Quickly view the contents of a Winmail.dat, MSG and XPS file with a tap on your space-bar via Quick Look

- Once extracted, files can be treated like any other file on your computer

Letter Opener speaks your language! It’s fully localized in Arabic, Chinese, Dutch, French, German, Hindi, Italian, Japanese, Korean, Portuguese, Russian, Spanish and Swedish.

- Winmail.dat Premium: Access to attachments in winmail.dat files
- MSG Premium: Access to attachments in MSG files
- XPS Premium: Convert XPS files to PDF files
- File Extension Premium: Fix files with the wrong or no extension

The trial allows you to use all premium-features 14 days for free! After the trial period you can keep reading message text. The premium add-ons can conveniently be purchased individually.

We provide direct personal support, so don’t hesitate to contact us if you have any questions or comments:

Thanks for helping us to keep improving Letter Opener!

What’s New

Version 9.2.1

- Improvements
- Added localizations
- Bug fixes

If you encounter any problems or have questions please go to Help > Feedback Assistant to send a report or contact us via email:

Please consider writing a short review or to rate Letter Opener. Thank you!

Ratings and Reviews

3.2 out of 5
226 Ratings
226 Ratings
jpwabbit ,

Problem Solved (Even for a Mac User

I received some important legal documents attached to an email on a weekend that were sent in a format I hadn’t seen before; win mail.dat. A Mac user, I was concerned I might not be able to reach the sender over the weekend and would have to wait until I could request the documents in a more common format. Without much confidence in succeeding, I checked to see how I might translate the format or find a utility that might allow me to access the information. Much to my surprise, Winmail.dat reader was available through the App Store. After a brief, successful download of the app and very user friendly experience with the trial version, I was happy to pay the very reasonable $9.99 for the premium version which allowed me to read and save the important legal documents as .PDF format documents. Problem solved.

Crone1942 ,

Winmail.dat Viewer - Letter Opener 9

This app has really simplified things for me when I get winmail.dat files. I can now open and read them! Yay!

RW68RSConv ,

Just works

It has never failed to open a win.dat file. What more is it supposed to do?


Atlan Creative GmbH
12.4 MB
OS X 10.9 or later, 64-bit processor
English, Arabic, Dutch, French, German, Hindi, Italian, Japanese, Korean, Portuguese, Russian, Simplified Chinese, Spanish, Swedish
Age Rating
Rated 4+
© 2017 Atlan Creative GmbH


  • Family Sharing

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

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