How to Open a DAT File on Mac

Opening a Winmail.dat or ATT0001.dat File

1. 
   Open the email with the attachment. Winmail.dat and ATT0001.dat files are usually email attachments from Microsoft email clients like Outlook that aren't properly formed.
2. 
   Click

   

   next to the attachment. This will display a drop-down menu with some options for the attachment.
3. 
   Click Save As. This will remove the attachment from the email and save it to your computer.
4. 
   Go to http://www.winmaildat.com in a web browser. You can use any web browser. Safari is the app that has a blue image that resembles compass.
5. 
   Click Choose File. It's the button next to "Upload a file" on the winmaildat.com page. This will open a file browser window that you can use to browse files and folders on your Mac and select a file.
6. 
   Select the winmail.dat or ATT0001.dat file. Use the file browser to navigate to where you saved the winmail.dat or ATT0001.dat file from your email client and click on it to select it.
7. 
   Click Choose. This will upload the file to winmaildat.com.
8. 
   Click Start. It's the blue button on the winmaildat.com page. The webpage will begin the process of extracting data from the file. Allow a few minutes for the process to complete.
9. 
   Download the data from the results page. Extracted files will be stored on the webpage for 30 minutes. If the results page is empty, no files were able to be extracted.