Data Protection Issues

How to Alert on External File Sharing Activity in Microsoft 365

Kushani Nimanthika Oct 7, 2026 869 views

Question details

A Microsoft 365 administrator needs to monitor and alert on external collaboration and possible external data sharing across Teams, SharePoint, and other file-sharing platforms.

How to Alert on External Teams, SharePoint, and File Sharing Activity

Product: Microsoft 365
Device & OS: not provided
Scenario: Configuring administrative alerts to track external file sharing and collaboration activities securely.
Observed behavior: The administrator aims to establish tracking, cross-tenant access alerts, and sensitivity label controls to ensure organizational data protection.

Before you start

Ensure you have the appropriate Microsoft 365 administrator permissions (such as Compliance Administrator) and licensing required to configure Microsoft Purview and Microsoft Entra settings.

Solution 1Recommended

Set Up Microsoft Purview Alert Policies

Use Microsoft Purview to create targeted alerts that notify administrators when users share files externally via SharePoint or Teams.

Microsoft Purview allows administrators to monitor a wide range of activities. Alert policies can be configured to automatically trigger notifications when sensitive data or standard files are shared outside the organization.

Log into Microsoft Purview

Open your web browser and sign in to the Microsoft Purview compliance portal using your global administrator or compliance admin credentials.

Navigate to Alert Policies

In the left navigation pane, go to 'Policies' and select 'Alert policies' to view existing configurations.

Create a New Policy

Click on 'New alert policy'. Assign a name and description, then choose the specific activity, such as 'Shared file externally' under the file and page activities category.

Define Settings and Save

Set the alert severity, define the conditions, and specify the email addresses of administrators who should receive the alerts. Click 'Save' to activate the policy.

Licensing Requirement: Advanced alert policies may require Microsoft 365 E5 licensing or specific compliance add-on subscriptions.

Solution 2

Configure Microsoft Entra Cross-Tenant Access Settings

Manage and monitor B2B collaboration and cross-tenant data sharing directly from the Entra admin center.

Solution 3

Apply Sensitivity Labels for Additional Control

Use sensitivity labels to classify data and enforce policies that prevent unauthorized external sharing.

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Frequently Asked Questions

Do I need a specific license to use Microsoft Purview alert policies?

Yes, the exact alerts available and the ability to configure advanced policies in Microsoft Purview depend on your Microsoft 365 licensing, such as an E5 license or specific Microsoft 365 compliance add-ons.

Can I monitor external sharing on individual SharePoint sites instead of the whole tenant?

Yes, when configuring Microsoft Purview alert policies, you can scope your policies to monitor sharing activities on specific SharePoint sites, particular users, or apply it tenant-wide depending on your security requirements.

What is the difference between Purview alerts and Entra cross-tenant settings?

Microsoft Purview alerts notify administrators passively when specific actions (like sharing a file externally) occur. In contrast, Microsoft Entra cross-tenant access settings proactively govern and restrict which external organizations your users are permitted to collaborate with.

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