Fix: Outlook Mobile Unable to Upload or Send Attachments Due to Intune App Protection Policies
In this scenario, devices were already enrolled and compliant, and a test policy without restrictions existed — but users still couldn’t upload files in Outlook. The issue was traced back to key data transfer settings within the App Protection Policy.
🔍 The Symptoms / Error Message
⚠️ What You May Experience
- Users are unable to upload attachments or send files from Outlook Mobile
- File picker may not display local files or other apps
- Upload process fails silently or attachments do not get added
🧠 Root Cause
💡 Data Transfer Controls in App Protection Policies
The issue occurs when data transfer controls within Intune App Protection Policies restrict how corporate data flows between applications and device storage. Even if a policy appears permissive, the following key settings can block uploads:
| Setting | Impact |
|---|---|
| Send Org Data to Other Apps | Restricts whether Outlook can pass data (attachments) to other apps |
| Save Copies of Org Data | Controls temporary storage required during upload |
| Receive Data from Other Apps | Determines whether Outlook can access files from storage or external apps |
⚠️ Why Uploads Fail
If these are set too restrictively (e.g., “Policy managed apps only”), file upload and attachment selection will fail.
🛠️ Step-by-Step Resolution
Option 1 — Fix via Intune Admin Center (Recommended)
Update the data transfer settings on the affected App Protection Policy.
✅ GUI Method
- Go to Microsoft Intune Admin Center at intune.microsoft.com
- Navigate to: Apps → App Protection Policies
- Select the affected policy (e.g., Outlook Mobile policy)
- Go to Data protection
- Configure the settings shown in the table below
- Click Review + Save
- Assign the policy (if not already assigned)
- Ask users to sync Company Portal and restart the Outlook app
| Setting | Recommended Value |
|---|---|
| Send Org Data to Other Apps | Policy managed apps |
| Save Copies of Org Data | Allow |
| Receive Data from Other Apps | All Apps |
💡 Important — These Are the Correct Values
If your environment already has these three values configured exactly as shown above (Policy managed apps / Allow / All Apps) and uploads still fail, the policy settings are not the cause — verify the assignment scope and check for conflicting policies next (see Option 3 below).
Option 2 — Validate Using Microsoft Graph PowerShell
Audit App Protection Policies programmatically to confirm what’s actually applied.
# Connect to Microsoft Graph Connect-MgGraph -Scopes "DeviceManagementApps.Read.All" # Get all App Protection Policies Get-MgDeviceAppManagementMobileAppConfiguration | Select-Object DisplayName, Id # Get detailed configuration for a specific policy $policyId = "YourPolicyID" Get-MgDeviceAppManagementManagedAppPolicy -ManagedAppPolicyId $policyId
⚠️ Note
App Protection-specific properties may require querying managed app policies or configurations differently depending on the platform (iOS/Android).
Option 3 — Check for Policy Conflicts
Sometimes multiple policies assigned to the same group can override expected behaviour.
✅ What to Check
- Review all policies assigned to the same user group
- Ensure no restrictive policy is assigned alongside the test policy
- Validate policy priority and targeting
💡 Best Practices & Recommendations
- Always test App Protection Policies with a pilot group before wide deployment
- Use “All Apps” for Receive Data when file uploads from local storage are required
- Avoid overlapping policies targeting the same users/devices
- Monitor behaviour using the Intune Troubleshooting blade (User → Device → App Protection Status)
✅ Final Notes
Even when policies appear correctly configured, attachment handling in Outlook Mobile is highly dependent on the data transfer pipeline defined by Intune APP settings. Ensuring that apps can send, receive, and temporarily store data is critical for successful file uploads.
If the issue still persists in your environment, the next step is to review Conditional Access policies or Outlook app logs, as they can also silently block data transfer.
📚 References & Further Reading
- 🔗 App protection policy settings — Android — Microsoft Learn
- 🔗 App protection policy settings — iOS — Microsoft Learn
- 🔗 App protection policies framework — Microsoft Learn
- 🔗 Monitor app protection policies — Microsoft Learn