Outlook Attachments Not Showing on iPhone? Here's the Fix
If you're missing Outlook attachments on your iPhone or iPad, seeing only a mysterious "winmail.dat" file, you're experiencing a common compatibility issue. This guide provides immediate solutions and explains why this happens.
⚡ Quick Fix (2 minutes)
- Download Winmail File Viewer from App Store
- Open the winmail.dat file with the app
- Access all your missing attachments instantly
The Problem: Why Attachments Disappear
What You're Experiencing
Someone sends you an email from Outlook with attachments
They attached PDFs, Word docs, images, or other files
You open it on your iPhone/iPad
Using Mail, Gmail, or another email app
Attachments are missing or show as "winmail.dat"
You can't access the files you need
📊 How Common Is This?
- • Affects millions of iOS users daily
- • Happens with 30-40% of corporate emails
- • Most common with Outlook 2016-2021
- • Occurs across all iPhone/iPad models
🔍 Root Cause
Outlook uses a proprietary format (TNEF) when sending in Rich Text Format. iOS Mail and most email apps can't decode this format, so attachments get bundled into an unreadable winmail.dat file.
Symptoms: How to Know If This Is Your Problem
Check if you have these symptoms:
Solutions: How to Access Your Missing Attachments
1Best Solution: Use a Winmail.dat Viewer App
The most reliable way to access your missing Outlook attachments is using a dedicated app that can decode the winmail.dat format. This works instantly and doesn't require any changes from the sender.
Why Winmail File Viewer?
- Opens files instantly
- Works offline
- 100% secure (local processing)
- No file size limits
- 4.8★ App Store rating
- One-time fix for all future emails
2Ask Sender to Change Format
Request the sender to resend the email in HTML or Plain Text format:
- In Outlook: File → Options → Mail → Compose messages → HTML
- Or when composing: Format Text tab → HTML
3Use Outlook App for iOS
Microsoft's Outlook app for iOS can sometimes read these attachments:
- Download Microsoft Outlook from App Store
- Add your email account
- View the email in Outlook app
4Forward to a PC
Forward the email to yourself and open on a Windows computer with Outlook
Prevention: How to Stop This from Happening
For Your Organization (IT Administrators)
If your company frequently sends emails to external recipients:
- Configure Exchange Server to send external emails in HTML format by default
- Set group policy to enforce HTML format for all users
- Train employees on proper email format settings
- Consider using email gateway solutions that convert TNEF automatically
For Individual Senders
Share these instructions with people who send you emails:
Change default format
File → Options → Mail → HTML format
Set for specific recipients
Add to contacts → Set "Send using Plain Text"
Check before sending
Ensure Format Text tab shows HTML, not Rich Text
Troubleshooting Common Issues
Still can't see attachments after using viewer app?
- Ensure you're opening the winmail.dat file, not the email itself
- Check if the sender actually attached files (they may have forgotten)
- Try forwarding the email to yourself and opening the forwarded version
- The attachments might be embedded in the email body instead
Attachments are corrupted or won't open?
- The original files may be corrupted
- Try saving the files first, then opening them
- Check if you have the necessary apps to open specific file types
- Ask the sender to verify the files work on their end
Some attachments show but others don't?
This happens when:
- Sender attached files at different times
- Mix of inline and attached files
- Some files exceeded size limits
- Partial TNEF encoding (some files in winmail.dat, others separate)
Frequently Asked Questions
Why does this only happen with Outlook emails?
Microsoft Outlook uses a proprietary format called TNEF (Transport Neutral Encapsulation Format) when sending emails in Rich Text Format. This format is not supported by Apple's Mail app or most other email clients, causing attachments to be bundled into an unreadable winmail.dat file.
Is this an iPhone/iPad problem or an Outlook problem?
It's a compatibility issue between Microsoft's proprietary format and standard email protocols. Neither side is technically "wrong" - Outlook uses its format for advanced features, while iOS follows standard email protocols. The solution is to use a tool that bridges this gap.
Will Apple ever fix this?
It's unlikely. Apple would need to license Microsoft's proprietary TNEF format, which goes against their approach of using open standards. This issue has existed for over a decade, so third-party solutions remain the best option.
Are my attachments safe when using a viewer app?
Yes, when using a reputable app like Winmail File Viewer that processes files locally on your device. Your attachments never leave your iPhone/iPad and aren't uploaded to any servers. Always check the app's privacy policy to ensure local processing.
Stop Missing Important Attachments
Get instant access to all your Outlook attachments on iPhone and iPad