If the DAT file is a video, you can open it with its associated video app. However, if you aren't sure what app it's intended for, VLC Media Player should be able to open it as well.

If you're having trouble opening a DAT file, I'll show you a simple and free way to do it. This method works on both Mac and PC. Just open your browser and go to winmaildat.com. It's a ...

In Windows 7 and earlier, Internet Explorer 9 and earlier, used the index.dat file to index all this information, including the Internet Cache, Cookies and History.

Via this procedure, Windows saves your latest preferences each time you make a change and lets multiple users use the same computer with their own preferences. The name NTUSER.DAT comes from Windows ...

Another approach is to download a program that can translate the winmail.dat file. Several developers have created helpful programs that can open the files.

If you can’t convince the sender to use standard email formats, you also have a few options for reading these Winmail.dat-formatted messages. On the Mac, TNEF’s Enough, can open winmail.dat files.