Data Protection Issues

How to Apply DLP and Block Microsoft Teams File Uploads

Olivia Miller Oct 10, 2026 870 views

Question details

The user needs to configure Data Loss Prevention (DLP) and access controls to block file uploads in Microsoft Teams.

How to Apply DLP and Block Microsoft Teams File Uploads

Product: Microsoft Teams
Device & OS: not provided
Scenario: Enforcing organizational data protection policies to prevent unauthorized file sharing via Microsoft Teams.
Observed behavior: Administrators find that third-party endpoint security products do not provide direct controls for blocking Teams uploads, requiring native Microsoft 365 solutions.

Before you start

Ensure you have administrative access to the Microsoft 365 admin center, Microsoft Purview compliance portal, and Microsoft Entra ID with the appropriate licenses (such as M365 E5) required for advanced DLP features.

Solution 1Recommended

Configure Microsoft Purview DLP and Entra Conditional Access

Utilize Microsoft's native Purview Data Loss Prevention combined with Conditional Access to monitor and block unauthorized file sharing in Teams.

Microsoft Purview DLP allows you to identify, monitor, and automatically protect sensitive information across Microsoft 365. By combining it with Conditional Access, you can enforce strict upload restrictions based on user, device, and location contexts.

Access the Microsoft Purview portal

Sign in to the Microsoft Purview compliance portal using your global administrator or compliance administrator credentials.

Create a new DLP policy

Navigate to Data loss prevention > Policies in the left sidebar and click on 'Create policy'. Choose a template or create a custom policy.

Select Microsoft Teams as the location

In the 'Locations to apply the policy' step, toggle the status for 'Microsoft Teams chat and channel messages' to ON.

Define protection rules

Set the conditions for the types of sensitive data to protect. Under actions, configure the rule to restrict access or block users from sharing the files in Teams.

Configure Conditional Access in Entra ID

Go to the Microsoft Entra admin center. Navigate to Protection > Conditional Access. Create a policy targeting Microsoft Teams to block access from non-compliant devices or unapproved apps.

Configure Microsoft Purview DLP and Entra Conditional Access

Solution 2

Apply Microsoft Intune Device and Access Controls

Use Microsoft Intune to restrict device access and prevent unauthorized file uploads on unmanaged or non-compliant devices.

Solution 3

Consult Third-Party Endpoint Security Support

If you rely on third-party security software (like Seqrite Endpoint Security), specific configurations may be needed as they often lack direct Teams account binding.

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Frequently Asked Questions

Can third-party antivirus completely block Microsoft Teams file uploads?

In most cases, standard third-party endpoint security products cannot directly inspect or block encrypted Microsoft Teams traffic without native integrations. You typically need to use Microsoft Purview DLP or a specialized Cloud Access Security Broker (CASB) for application-layer control.

Does Microsoft Purview DLP require a specific license?

Yes, configuring Data Loss Prevention policies specifically for Microsoft Teams chat and channel messages generally requires advanced compliance licenses, such as Microsoft 365 E5 or the Information Protection and Governance add-on.

How do I stop guest users from uploading files in Teams?

You can prevent guest uploads by navigating to the Microsoft Teams admin center, selecting Users > Guest access, and disabling file sharing capabilities. Additionally, you can enforce Entra Conditional Access policies to block non-employees from accessing cloud storage.

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