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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

Great solution

I use a Mac. For years I had no problem with MS using clients sending me data. Recently however files they are sending are in .dat format. So far letter opener is simply brilliant. I have had absolutely no problems using it.

Essential when using a Mac

as a stand alone or Mail plug in this is an essential tool - saves heartache and hassle and works every time

It does what it says it will

My husband has a PC and I have a Mac. This is very necessary for us. Especially for calendar attachments from him.

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
  • Developer:

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