Troubleshooting
Outlook Attachments Missing on iPhone? Fix Winmail.dat
When an Outlook attachment arrives as winmail.dat, the files are inside a TNEF container your iPhone cannot open on its own. Winmail File Viewer extracts them on-device.
Free message viewing · Purchase required for attachments
Quick fix
- Install Winmail File Viewer from the App Store.
- Open the winmail.dat attachment and tap Share.
- Choose the app to reveal the missing files.
Is this your problem?
The only attachment is winmail.dat. The sender confirms they attached files. The same email shows its attachments on a PC but not on iPhone or iPad. Attachment icons look greyed out, or the count does not match what was sent.
Why it happens
Outlook sent the message in Rich Text Format, so it bundled the formatting and attachments into a TNEF container. iOS Mail cannot decode TNEF, so it shows the container instead of the files.
What is winmail.dat? →How to get the attachments
Use the viewer app. It decodes the container on your device with no upload, and it recovers the original files on the phone.
If you only need the text, read the message free in the online viewer. You can also ask the sender to resend the files as ordinary attachments, or open the message on a computer running Outlook.
How to prevent it
Senders can switch from Outlook Rich Text to HTML or plain text, for everyone or just for you. Administrators can disable TNEF for external recipients.
Frequently asked questions
Is this an iPhone problem or an Outlook problem?
It is an Outlook format choice. iOS Mail cannot decode TNEF, so the fix is on the sending side or with an app that can.
Are my attachments safe in a viewer app?
With Winmail File Viewer, decoding happens on your device and the file is never uploaded. Only open attachments from senders you trust.