Permission & Access Issues

How to Use SharePoint as a Secure File Drop Box

Tauseeq Magsi Oct 10, 2026 869 views

Question details

Configure a SharePoint document library to act as a secure drop box where anonymous users can upload files without seeing others' submissions.

How to Use SharePoint as a Secure File Drop Box

Product: Microsoft SharePoint
Device & OS: not provided
Scenario: Creating an external file drop box for anonymous internet users to securely submit documents.
Observed behavior: SharePoint lacks an out-of-the-box setting to allow anonymous file uploads while automatically preventing those users from viewing or editing files uploaded by others.

Before you start

Ensure you have site owner privileges in your SharePoint environment and the necessary licensing to create and run Power Automate flows.

Solution 1Recommended

Use Power Automate to Remove Permissions Dynamically

Since SharePoint does not offer a native drop box setting, you can build a Power Automate flow that automatically strips viewing and editing permissions from newly uploaded files.

This solution involves granting standard upload access to your target audience, then immediately using a cloud flow to remove their permissions once the file lands in the library. This simulates a write-only drop box.

Create a dedicated document library

In your SharePoint site, create a new document library specifically for external uploads and generate an 'Anyone with the link can edit' sharing link, or grant specific external users contribute access.

Create a new Power Automate flow

Log into Power Automate and create an 'Automated cloud flow'. Set the trigger to 'When a file is created (properties only)' and point it to your new SharePoint library.

Add the permission removal action

Add a new action in the flow by searching for 'Stop sharing an item or a file' in the SharePoint connector. Configure it using the ID of the newly uploaded file to remove all external contributor access.

Save and test the workflow

Save your Power Automate flow. Using an external test account or incognito browser, upload a test file to the library and verify that the file's permissions are automatically restricted after upload.

Use Power Automate to Remove Permissions Dynamically

Security Verification: Always test the workflow carefully before sharing the upload link publicly to ensure there is no delay or failure that might briefly expose uploaded files to other anonymous users.

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Frequently Asked Questions

Can I make a SharePoint folder write-only without using Power Automate?

No, SharePoint does not currently offer a native 'write-only' or 'drop box' permission level for folders. You must use a workaround like Power Automate or a third-party form solution to achieve this.

What happens if my Power Automate flow fails during an upload?

If the flow fails to trigger or complete, the uploaded file will retain the default inherited permissions of the folder. This means other users with the upload link might temporarily be able to see or modify that file until the permissions are manually corrected.

Is it possible to use Microsoft Forms instead of a SharePoint library drop box?

Yes, Microsoft Forms includes a 'File Upload' question type that securely saves files to a backend SharePoint or OneDrive folder. However, this is typically restricted to internal users within your organization and may not work for anonymous external uploads depending on your tenant settings.

Document & File Issues