This app can't open my Winmail.dat file!
We are sorry that we have been unable to help.
If your file is named "winmail.dat" or "ATT01.dat" and you still can't open it, you can help us improve our app by sending us your file to email@example.com for inspection.
If your file has a different name, then it is probably not a TNEF file. There are many file types with a .dat extension. We can't open all of them, only the so-called TNEF files. Giving us a bad rating or review in this case might only help you vent your anger, but it is just like complaining that you can't use a hammer to turn a screw.
What are those Winmail.dat files?
When people send messages from incorrectly configured Microsoft Outlook email clients or via an incorrectly configured Exchange Server, a file attachment called winmail.dat may be added as an attachment to the email. In some cases, the email body itself doesn't contain any text at all.
These winmail.dat files (sometimes also named ATT.DAT) contain formatting information for messages that use Microsoft's proprietary TNEF standard and, if there are any attachments, they are removed from the email and added to the winmail.dat file. Besides Outlook, there are very few email clients which are able to open those files.