. DAT is not a standard file. Many softwares use this extension, but files have different meanings. For example, a VCD file is. DAT, many data analysis software also use this extension to save data. So it depends on the specific software situation.
If the email file you receive is WinMail. DAT, which means that it is in TNEF format sent by Outlook. You can release files in WMDecode when downloading. This software doesn't need to be installed, just copy WMDecode.exe to the computer. Run the runtime on the command line:
WMDecode yours. Dat file name.
For more detailed instructions, please refer to the readme file.
This kind of download is generally not available online.
Want to open it?
You can use a player such as "Hero Solution" or "Storm Video". These two players are everywhere on the Internet. You can also try using Notepad.