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How to Fix Winmail.dat PDF Opening Issues on iPhone
Question details
The user is unable to open PDF attachments on an iPhone because the files are being received as unreadable winmail.dat files.
- Product
- Mail / PDF Reader
- Device & OS
- iOS
- Scenario
- Receiving an email containing a PDF attachment and attempting to view it on a mobile device.
- Observed behavior
- The PDF attachment is automatically converted into a winmail.dat file, preventing the user from opening or reading the document.
Check if this issue occurs with all PDF attachments or only with those sent from a specific contact using Microsoft Outlook.
Request Sender to Adjust Outlook Settings
The root cause is the sender's Microsoft Outlook sending emails in Rich Text Format (RTF). The most reliable fix is for the sender to change their email format.
When an email is sent from Microsoft Outlook using the proprietary Rich Text Format, non-Outlook email clients (like the iOS Mail app) cannot decode the formatting and attachments. This results in standard files, like PDFs, being wrapped into a single unreadable winmail.dat file.
Ask the sender to open Microsoft Outlook on their computer and navigate to File > Options.
In the Outlook Options window, click on the Mail tab. Under the 'Compose messages' section, change the 'Compose messages in this format' dropdown menu from Rich Text to HTML or Plain Text.
If the issue only happens with your email address, the sender can double-click your email address in their Contacts, open the email properties, and select 'Let Outlook decide the best sending format' or force 'Send Plain Text only'.
Have the sender attach the PDF to a new email and send it again. It should now arrive as a standard, readable PDF.
Use a Winmail.dat Viewer App on iPhone
If you cannot contact the sender to change their settings, you can use a third-party app to extract the PDF from the winmail.dat file directly on your iPhone.
Switch to WPS Office for Seamless Document Sharing
Avoid proprietary formatting issues by using WPS Office. It provides a lightweight, highly compatible alternative to Microsoft Office, ensuring your PDFs and documents are universally accessible without the hassle of winmail.dat errors.
- 1. Download WPS Office: Visit the App Store or the official WPS website to download WPS Office for free.
- 2. Access your documents: Open the app and easily import standard PDFs, Word documents, or spreadsheets directly from your local storage or cloud drive.
- 3. Read and share seamlessly: Use the integrated PDF tools to read, annotate, and share your documents in universally accepted formats.
Frequently Asked Questions
What exactly is a winmail.dat file?
A winmail.dat file is a proprietary attachment format created by Microsoft Outlook when an email is sent using Rich Text Format (RTF). It encapsulates the email's formatting and actual attachments (like PDFs), making it unreadable to non-Outlook email clients.
Can I prevent my iPhone from receiving winmail.dat files?
Because the winmail.dat format is generated on the sender's end before the email is even sent, you cannot prevent receiving them through iPhone settings. The only true fix is asking the sender to configure their Outlook to send emails in HTML or Plain Text.
Does the built-in iOS Mail app support winmail.dat files?
No, the default iOS Mail app does not natively decode winmail.dat files. To view the contents, you must either have the sender resend the file in a standard format or use a dedicated third-party extractor app from the App Store.
