How to open winmail.dat file on Windows

If you are here, it means that you’ve received an empty email with the attachment winmail.dat. You are wondering: what is it and how to open it? A winmail.dat file or (TNEF) is a special attachment type sent by Microsoft email applications. Many email client applications like Thunderbird cannot open them. The Winmail.dat Reader is a free application that allows you to open any winmail.dat file.

Open winmail.dat attachment on Windows without installation

If you received a winmail.dat file only once, you probably don’t need to install an application just to open it. If that’s the case, you can use the online Winmail.dat Reader. You can learn how to read a winmail.dat attachment through the online reader here.

Open winmail.dat files natively on Windows

If you receive winmail.dat files all the time, you might consider installing the Winmail.dat Reader on your PC and associating it with .dat file extensions. This way you can open the TNEF attachments with one mouse click.

Another reason you might want to install the Winmail.dat Reader on your computer is security. By using any online service you are uploading the attachment file to an internet to decode it. If you believe that your attachment has sensitive or business relevant data, you should consider installing the winmail.dat reader locally.

Follow the steps below To install and run the Winmail.dat Reader on Windows 10, Windows 7, Windows 95, or 98.

Time needed: 1 minute.

Decoding a winmail.dat file on Windows

  1. Download the Winmail.dat Reader

    In your web browser, open www.winmail-dat.com and click to download the Winmail.dat Reader for Windows

  2. Launch the Winmail.dat Reader installer

    Click on the downloaded file and select Open to launch Winmail.dat Reader installation. If you receive a warning “Do you want to allow this app from an unknown publisher to make changes to your device?” just click Yes.

  3. If you receive a warning

    “Do you want to allow this app from an unknown publisher to make changes to your device?” click on Yes.
    “Windows protected your PC” just click on More Info and then on Run anyway

  4. Install the application

    Accept the License Agreement and click on install.

  5. Associate .dat files with the Winmail.dat Reader

    After the installation, run the Winmail.dat Reader. The first time you open it, you will be prompted with the settings window. Click on Associated .dat files with this application and press OK.

  6. Open the winmail.dat file

    In your email client, select to open the winmail.dat file you’ve received as an attachment. The Winmail.dat Reader will open automatically and decode the file for you.

How to open winmail.dat file on Windows

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