How to Open WinMail.dat Files?

in Microsoft by

Open Winmail.dat file

Q: I got an email which supposed to be arrived with photo(s) attachment. The sender said that he only sent me JPEG files, nothing more. But when I try to open this attachment, winmail.dat file, Windows tells me that I don’t have necessary programs to open such file.

Tried to change the file extension from winmail.dat to be winmail.jpg but it didn’t work. I’m using Microsoft Outlook. Can you recommend me what programs do I need to install to open winmail.dat file? Cannot ask the sender to do more than this.

A: Well, it’s an old common problem but still quite depressing. The winmail.dat file exist when someone sending an email using a particular combination of Microsoft Outlook and Microsoft Exchange as sending/receiving server and preparing email in RTF format (probably when copy&paste the photo straight to email’s body).

Basically, Microsoft Exchange server takes the RTF formatting information and encodes it using a proprietary Microsoft Protocol called Transport Neutral Encapsulation Format (TNEF).

Transport Neutral Encapsulation Format (TNEF)

Unless the recipient is also using a combination of Microsoft Outlook and Microsoft Exhange, then a winmail.dat is the result because the receiver cannot parse the TNEF information from the sender.

In order to open winmail.dat file you may need an online tool such as and use this service to extract the contents of winmail.dat file you received.

Click Choose File button on that site, select the winmail.dat file you want to open and then click Open → Send file.

You can download the expected photo if it’s listed by clicking on it.

Other option you may use is by installing a freeware by EOLsoft, called Winmail Opener.

Winmail Opener Program

Winmail Opener Program

Hope this answer resolves your problem in regards to opening winmail.dat file.

Febryan Paudi (940 Posts)

Febryan Paudi is Apple enthusiast. Falling in love with Apple-tech since 2008, loves Blogging since high-school. Google+

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