Compliance Problems

How to Fix SSN DLP Policy Not Detecting Patterns in Microsoft Purview

Emma Brown Sep 30, 2026 869 views

Question details

The user needs to resolve an issue where a Microsoft Purview Data Loss Prevention (DLP) policy is failing to detect all regular expression patterns for Social Security numbers in emails and attachments.

Fixing SSN DLP Policy Pattern Detection Issues in Microsoft Purview

Product: Microsoft Purview
Device & OS: not provided
Scenario: Configuring a DLP policy to detect SSNs in email subjects, bodies, and attachments in order to display policy tips and send approval notifications to managers.
Observed behavior: The DLP policy does not recognize all valid SSN regular expression patterns, causing certain sensitive emails to bypass detection and approval workflows.

Before you start

Ensure you are logged into the Microsoft 365 admin center with Global Administrator or Compliance Administrator privileges, as standard user accounts cannot view or modify backend Purview settings.

Solution 1Recommended

Escalate to Microsoft 365 Support for Backend Inspection

Because Purview DLP pattern detection relies on Microsoft 365 backend configurations and regex engines, contacting Microsoft Support is necessary when standard detection rules fail to trigger.

Public forum moderators and standard administrators do not have access to the backend server logs required to diagnose why certain regular expressions fail to match in Purview. A dedicated Microsoft 365 support engineer can inspect your tenant configuration, trace policy matches, and review backend telemetry.

Log in to the Microsoft 365 Admin Center

Navigate to admin.microsoft.com and log in using an account with Global Administrator permissions.

Access the Help & Support Portal

On the left-hand navigation menu, click on the 'Support' dropdown and select 'Help & support'.

Describe the DLP Issue

In the search box, type 'Purview DLP SSN pattern not detecting' and press Enter. Review any automated solutions provided.

Open a Service Request

If the automated solutions do not resolve the issue, click 'Contact support' at the bottom of the pane. Fill in the details of your regular expression issue and submit the service request.

Escalate to Microsoft 365 Support for Backend Inspection

Reseller Purchases: If your Microsoft 365 subscription was purchased through a third-party reseller (CSP), you must contact the reseller directly for technical support and escalation.

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Frequently Asked Questions

Why is my Microsoft Purview DLP policy missing some SSN formats?

DLP policies rely on specific built-in sensitive information types (SITs) or custom regular expressions. If users type SSNs in unexpected ways (such as missing dashes or adding spaces), the Purview regex engine might not trigger a match unless your custom SIT specifically accounts for those variations.

Can I safely test a new Purview DLP policy before fully enforcing it?

Yes, Microsoft Purview allows you to run DLP policies in 'Test it out' mode. This lets you monitor policy matches in backend reports to confirm your SSN regex patterns are working without blocking emails or interrupting user workflows.

How do I ensure policy tips are activated for my DLP rule?

In the Microsoft Purview compliance portal, edit your active DLP policy. Navigate to the 'User notifications' section within the specific rule settings, and make sure the toggle for 'Notify users in Office 365 services with a policy tip' is turned on.

Why can't community moderators help fix my DLP pattern detection issue?

Community forum moderators lack the security clearance and backend access to view private tenant configurations, sensitive detection rules, or server logs. Complex regex failures in Microsoft 365 require a formal support ticket so engineers can inspect your specific environment.

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