How to Open Winmail.dat Files on iPhone & iPad
Quick answer:
To open winmail.dat on iPhone, use the iOS share sheet to send the attachment to Winmail File Viewer, then view or save the hidden Outlook attachments.
- Open the email with the winmail.dat attachment.
- Tap the winmail.dat file.
- Tap the Share button.
- Choose Winmail File Viewer.
- View, save, or share the extracted attachments.
Can't open winmail.dat files on your iOS device? This comprehensive guide shows you exactly how to access all hidden attachments in just a few taps. Works with all iPhone and iPad models.
In This Guide:
Why Do I Receive Winmail.dat Files?
Winmail.dat files are created when someone using Microsoft Outlook sends you an email in Rich Text Format (RTF). This proprietary format, also known as TNEF (Transport Neutral Encapsulation Format), packages the email's formatting and all attachments into a single file that iOS Mail and most email clients can't open natively.
Common Scenario: Your colleague sends you important documents from Outlook, but all you see is a mysterious "winmail.dat" file that won't open on your iPhone or iPad.
If you already received one, you can still extract the original attachments on iPhone with an on-device viewer.
How to Open Winmail.dat Files on iPhone and iPad
Download Winmail File Viewer
Open the App Store on your iPhone or iPad and search for "Winmail File Viewer" or tap the link below:
Open Your Email
Go to your Mail app and find the email containing the winmail.dat file. You'll see it listed as an attachment.
Tap the Winmail.dat File
Tap on the winmail.dat attachment. iOS will show you a preview screen with sharing options.
Select "Open in Winmail File Viewer"
Tap the share button and select "Winmail File Viewer" from the list of apps. The file will automatically open in the app.
View and Save Attachments
All hidden attachments are now visible! You can view, save, or share any document, image, or file that was contained in the winmail.dat file.
Want the fastest method? Use Winmail File Viewer to open the file directly from the iOS share sheet and extract the hidden attachments on your device.
Can iPhone Open Winmail.dat Files?
iPhone and iPad cannot open winmail.dat files natively in Apple Mail because the file uses Microsoft's TNEF format. A dedicated viewer can decode the container and reveal the original attachments.
How Do I Open a .dat File on iPhone?
If the file is named winmail.dat, it usually came from Outlook and may contain PDFs, Word documents, images, or spreadsheets. Open it from Mail or Files with the iOS share sheet, then choose Winmail File Viewer to extract the contents.
How Do I Extract Outlook Attachments on iPhone?
Tap the winmail.dat attachment, share it to Winmail File Viewer, and the app will show the files hidden inside. You can then open, save, or share each extracted attachment from your iPhone.
Are There Alternative Ways to Open Winmail.dat?
Method 2: Ask the Sender
Request the sender to resend the email in HTML or plain text format instead of Rich Text Format. They can change this in Outlook's message format settings.
⚠️ Drawback: Requires action from the sender and may not always be practical.
Method 3: Use a Computer
Forward the email to yourself and open it on a Windows computer with Outlook installed.
⚠️ Drawback: Requires access to a computer and is not convenient for mobile users.
Why Winmail File Viewer is the Best Solution
Online converters may require uploading private attachments. For sensitive business, legal, medical, or financial files, use an on-device viewer instead.
- Instant access - no waiting or forwarding emails
- Works offline - no internet connection needed
- 100% secure - files stay on your device
- One-time solution - works for all future winmail.dat files
How Can I Prevent Receiving Winmail.dat Files?
While you can't control how others send emails, you can share these tips with frequent senders:
For Outlook Senders:
- Go to File → Options → Mail
- In the "Compose messages" section, change format to "HTML" or "Plain Text"
- For individual recipients: Create a contact and set "Internet Format" to "Send Plain Text"
- Disable Rich Text Format for all external recipients in Exchange settings
Why Did My Attachment Become Winmail.dat?
The sender's Outlook or Exchange settings packaged the original attachment into a winmail.dat file. The attachment did not disappear; it is hidden inside the TNEF container until you extract it with a compatible viewer.
Frequently Asked Questions
Is it safe to open winmail.dat files?
Yes, winmail.dat files themselves are not dangerous. They're simply containers for email attachments. However, always be cautious about the actual attachments inside, just as you would with any email attachment.
Why can't iPhone open winmail.dat files natively?
Winmail.dat uses Microsoft's proprietary TNEF format, which Apple's Mail app doesn't support. This format is specific to Outlook and requires specialized software to decode.
Will I lose any data when extracting files?
No, Winmail File Viewer extracts all attachments in their original format without any data loss. All documents, images, and files remain intact.
Do I need to pay for the app?
Winmail File Viewer offers a free version with basic functionality. Premium features are available through optional subscriptions for users who need advanced features or unlimited use.
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