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To download Winmail.dat Viewer - Letter Opener 4 from the Mac App Store, you need a Mac with OS X 10.6.6 or later. Learn More.

Winmail.dat Viewer - Letter Opener 4

By Atlan Creative GmbH

Open the Mac App Store to buy and download apps.


Letter Opener - Open winmail.dat, .msg and .xps files.
• Browser attachment of a winmail.dat file like other attachments
• Preview of winmail.dat using QuickLook
• Convert nested messages
• Convert Schedules, Appointments and Task for iCal
• Convert Contacts for Address Book
• Convert Notes
• Convert Delivery receipts and read receipts

Please refrain from sending your bug reports or feature requests using the App Store. Instead, to ensure a direct response from us send them to We’re always happy to help our users and receive their comments!

What's New in Version 4.0.1

• New Icon.
• Bug fixes and improvements.

If you like Letter Opener, please consider leaving a review. That helps us a lot. Thanks!


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Customer Reviews

It just works

I have been using this app for years. Opens up when needed and quickly converts .dat files. Highly recommended!

Simple solution

I’ve only needed this a handful of times, but it’s an indispensable tool for me. It’s super simple, and reliably converts emails saved in formats that my Mac can’t otherwise read. I’m a happy user.

It works !!!

It seems to open the windows files that are otherwise unviewable on my Mac, very easy to use and it just works as advertised, great App.

Winmail.dat Viewer - Letter Opener 4
View in Mac App Store
  • Free
  • Category: Productivity
  • Updated:
  • Version: 4.0.1
  • Size: 14.1 MB
  • Languages: English, Dutch, French, German, Italian, Japanese, Korean, Portuguese, Russian, Simplified Chinese, Spanish, Swedish
  • Seller:

Compatibility: OS X 10.9 or later, 64-bit processor

Customer Ratings

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Top In-App Purchases

  1. Winmail.dat Premium$9.99
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  4. File Extension Repair Premium$4.99