How to Open Winmail.dat File on Mac [Free Online Include]

Connie Wisley
time September 22, 2021 Preview 12.1K
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For Mac users, in the process of emailing with Windows users, you might receive emails with .dat file extension. Many Mac users have encountered the problem of failing to open Winmail.dat files on Mac. This article will show you what is Winmail.dat file and how to open Winmail.dat file on Mac in 3 different ways.

The main content of this article consists of five parts:

What is a Winmail.dat File?

I sometimes receive e-mail messages with a “winmail.dat” file attached that I cannot open. Why does this happen, and what can I do to fix it?

The winmail.dat file exist because various email programs cope with message formats differently. Winmail.dat file is a proprietary email format created by Microsoft/Windows Exchange Server, which contains rich-text formatting and packs all the original email information (subject, body, attachment) in the file. Non-Microsoft email systems cannot recognize rich text format, which causes the original emails to be packaged as Winamil.dat attachments, and therefore users cannot open the Winmail.dat file directly. 

Anyway, if you want to open Winmail.dat files on mac, you can try following 4 solutions according to your basic need.

How to Open Winmail.dat File on Mac?

To open Winmail.dat files on a Mac, a Winmail reader is needed. Though not that large in quantity, there are still some top Winmail viewer for mac available for choice.

Here I highlyt recommend you Cisdem Document Reader. It is a top-notch solution for you to open Winmail.dat files on Mac, and allows any attachments contained in the W.  inmail.dat files to be previewed and saved to your computer. Even, it lists all the files in list view under one window, so you don't have to switch among different windows when opening multiple Winmail.dat files at the same time.

More than just a Winmail.dat Reader for Mac, Cisdem Document Reader is also a kit helping open different documents simultaneously on Mac, such as XPS, OXPS, WPD, WPS, VISIO, PDF and DJVU, with a set of tools offered to optimize reading experience. Besides, it can precisely present the original text style, graphics, hyperlinks, layout, images and formats.

In additional, Cisdem Document Reader provides users with extended features to well manage these files, such as:

  • Extract images from supported files;
  • Print out as papers or print as PDF;
  • Export supported documents to PDF, Text, JPEG, PNG, RTFD, ect.  For example, converting VISIO to PDF, WPD to PDF, XPS to PDFDJVU to PDF, PDF to images and so on;
  • Bookmark and search within files;

Tutorial to Open Winmail.dat File on Mac:

Step 1. Download and install Cisdem Document Reader on your mac. It is lightweight and safe to download. 
Free Download

Step 2. Click Open File or drag-n-drop to open Winmail.dat file on your Mac.

open winmail on mac 02

Step 3. Use the toolbars to read Winmail.dat files on Mac.
All contents of Winmail.dat, including email message and attachments will be presented. With this product and its list view, you can open and view multiple Winmail.dat files at the same time. Moreover, you are able to switch between multiple Winmail files easily. 

open winmail on mac 03

Download Cisdem Document Reader now, and stop opening winmail.dat files without viewing the attachments. It works fluently, which helps you improve efficiency significantly.


1. Easy to use;

2. No ads, high security and no leakage of email privacy;

3. View Winmail.dat directly without downloading;

4. Open Winmail.dat files quickly in batches.

5. No file limit.


1. It is not free.

Check the video to open Winmail.dat file on Mac Now!

How to Open Winmail.dat File on Mac Free?

If you don’t need to open the Winmail.dat file on your Mac frequently, or if you don’t deal with a large number of files and prefer a free method, you can use this free application —— TNEF’s Enough.

Tutorial to Open Winmail.dat File on Mac Free:

Step 1: Make sure you have download and install TNEF’s Enough app on your Mac first;

Step 2: Download and save the Winmail.dat file to your computer, you can use TNEF's Enough from the “Open As” menu or drag and drop the Winmail.dat file into the application.

Step 3: Then a new window will pop up that show the original email info and attachment, you can double click the attachment to save it to your Mac.

open winmail.dat file via tnef enough


1. It’s free to use;

2. Support Mac, iPhone, iPad and iPod Touch.

3. No ads.


1. Fail to open Winmail.dat files occasionally;

2. Poor tech support;

3. Does not support opening and viewing Winmail.dat directly in the app.

How to Open Winmail.dat File on Mac Online?

Also, if you just need to open one or two Winmail.dat files and don’t want to specifically download third-party tools, you can utilize online free Winmail.dat reader. According to our test, Winmail.dat Reader is a convenient choice to view Winmail.dat file. It provides 2 ways for users to upload a winmail.dat file for viewing: choose from local computer or enter URL.

Tutorial to Open Winmail.dat on Mac Online:

Step 1. Open your browser to, upload Winmail.dat files from computer or enter the URL;

Step 2. Click “Start” to get the winmail.dat file in RTF format;

upload winmail.dat file to winmail.dat reader

Step 3. After that, the message body and original email attachment will display;

download message body to your computer

Step 4: To open the RTF file, you need to download the message body first.


1. It’s free;

2. No need to install any third-party tool.


1. File size larger than 50MB is not supported;

2. Ads on the website and there is a risk of information leakage;

3. The speed of opening files depends on network conditions.

4. Does not support batch open.

Extended: How to Open Winmail.dat File on iPhone?

As smartphones become more and more powerful, people are also increasingly inclined to handle their emails on their iPhones and iPads. As with opening Winmail.dat files on Mac, opening the Winmail.dat files on an iOS device also requires access to third party tools, useful app for iPhone/iPad is described below along with tutorial for your reference.

Winmail DAT File Viewer Pro


Step 1: Search and download Winmail DAT File Viewer Pro to your iPhone in the App Store;

Step 2: Launch the Mail App on iPhone and open the email that contains the Winmail.dat attachment;

Step 3: Then select the Winmail DAT File Viewer Pro to open the Winmail attachment.    

open winmail.dat file on iphone


1. Easy to use;

2. Support English, French, German and 15 more languages;

3. Allows your extracted attachment data to be sent via email and also saved to Drive, Mail, Facebook, Twitter, etc.


1. It is not free, $1.99 needed to get this app;

2. Only the "winmail.dat" file with TNEF encoding can be opened, not applicable to other files with the ".dat" extension.


For sure, there are more options out there to open Winmail.dat files on Mac. However, in the light of the simplicity, performance and feedback from users, most users pick Cisdem Document Reader as the ideal program to open and view Winmail.dat files on mac. 

Now, try Cisdem Document Reader, then all your problems will be gone.

Free Download

Connie Wisley
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Connie has been writing for Mac productivity and utility apps since 2009. Each review and solution is based on her practical tests, she is aways energetic and trustworthy in this field.

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  • Doras

    Great tool, I can also view the attachments of winmail.dat files. Thanks.

    6 years ago Reply

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