WinDat Opener has been the top rated winmail.dat decoder app for compatibility and reliability on the App Store since 2011. WinDat Opener opens the "winmail.dat" email attachments that are sometimes sent by Microsoft email systems. These file are in “TNEF” format, and usually contain attachments such as spreadsheets or presentations embedded within them. WinDat Opener extracts the embedded attachments hidden inside the winmail.dat file, allowing you to preview then right in WinDat Opener, or open them with another app.
There's also a version of WinDat Opener for the Mac.
Easy to use
WinDat Opener for iOS has been entirely rewritten for iOS 11. It's fully integrated with the iOS 11 File Manager app, so you can use it instantly.
Access any file
WinDat Opener is deeply integrated with iOS, so it can access any file that is reachable by iOS - DropBox, iCloud, anything that Apple's own File Manager app can see, WinDat Opener can also interact with.
Drag and Drop
WinDat Opener has full support for drag-and-drop on iPad's under iOS 11. Just drag files to and from the app. It's that easy.
Decodes any winmail.dat file
WinDat Opener will open any winmail.dat file. International character sets - no problem. Embedded Windows Mail notes - no problem. HTML or RTF formatted messages - no problem.
Extracts meeting requests and contact files
WinDat Opener extracts meeting requests and apointments as iCal files, and contacts information as vCard files. Single apointments, recurruring apointments, etc.
You can preview the contents of most common files, including Word, Excel and Powerpoint files, right inside WinDat Opener.
What are TNEF files?
Microsoft e-mail programs written for Windows, such as Outlook, sometimes send e-mails in the Transport Neutral Encapsulation Format (TNEF). Most other e-mail programs, including Apple Mail and Microsoft Entourage, do not understand TNEF. If your e-mail program doesn't understand TNEF, instead of seeing the e-mail and/or attachment, you may only see an attachment named "winmail.dat" or "Part 1.2" that you cannot open. Also, sometimes you may receive a TNEF attachment with a generic name such as ATT00008.dat or ATT00005.eml instead. While almost all attachments named "winmail.dat" are TNEF, you could receive non-TNEF attachments with names ending ".dat" or ".eml", or which are named or labeled "Part 1.2".
iOS 11 or later on the iPhone or iPad