Open a Winmail.dat File

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If you receive an email from an Outlook user in RTF format and open it with another email service, it's likely that any attachments will appear as a winmail.dat file. RTF is not taken into account by many email services and will require an additional step to access the documents.

Download LookOut

One way to open a winmal.dat file is by installing the plugin LookOut for Thunderbird, which is free and open source. This tool will automatically decode the winmail.dat file displayed in the e-mail and will present a list of the files contained in the winmail.dat attachment.

Download Fentun

You could download Fentun, a software that allows you to decode winmail.dat files. To get started, save the program on your computer. Open your email with the attachment, then right-click on the winmail.dat file.

Now, select Open, and then browse to find fentun.exe. In Fentun, select the file in the right window. You can see by its extension that it is already recognized and converted.

Finally, click Extract as to chose the location where to save.

Download WMDecode

You could download WMDecode to decode a winmail.dat file. This is a paid application with a restricted free trial. This tool decompresses the files found in the attachment by saving the winmail.dat file in the WMDecode directory. To access the document, launch WMDecode and the files well be extracted in the same directory.


If you prefer not to use a 3rd party application, you can ask your correspondents to send messages in Text only format, which will cause Outlook to stop sending winmail.dat files.

To send messages as text only, open Outlook, go to the Options menu, click Mail, and find the section Message format. Find the line When sending messages in Rich Text format to Internet recipients: and select Convert to Plain Text format.

Image: © Thunderbird.
Jean-François Pillou

Jean-François Pillou - Founder of CCM
Better known as Jeff, Jean-François Pillou is the founder of He is also CEO of CCM Benchmark and digital director at the Figaro Group.

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