The Winmail.dat opener is a free app for your Android phone. It allows you to open emails that have been sent to you through Outlook, which uses a rich text format instead of simply a text format. Therefore, without a way to open these files or attachments, you may not be able to read the email in your current email server.

Something to Consider

Not every file with a .dat extension is a Winmail.dat file. There are many other types of .dat files that will not open with the Winmail.dat opener. This app only opens the Winmail.dat files.

Another thing to consider is that sometimes, when you do open the file, there is nothing there. That may be because there is no attachment, yet you see the Winmail.dat extension. In this case, the opener may be storing style and format information. At any rate, this is a useful app when you understand what it does and how it works.