Start with text editing software like Windows' built-in Notepad app, or other similar third-party apps like Notepad++. Right-click on the DAT file you want to open and select Open with from the ...

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 ...