💡 Our Technical Review in summary
Summary
- Microsoft Purview is launching Classifier Simulation Mode, the initial phase of a new Classifier Health Monitoring Platform.
- This feature allows IT administrators to test and validate custom classifiers against production data in a non-production-impacting “simulation” state before official deployment.
- The primary goal is to provide a centralized environment to optimize classifier logic, reduce false positives, and minimize scanning latency or “noisy” matches.
- Timeline: Public Preview begins early March 2026, with General Availability (GA) expected by late May 2026.
Impact
- Administrative Workflow: Admins managing Microsoft Purview Information Protection and custom Sensitive Information Types (SITs) will see a new “Simulate” option. Simulation is optional but recommended; admins can still choose to publish directly.
- Performance Monitoring: All custom classifiers (even those published without simulation) will be continuously monitored for health. Inefficient classifiers that cause significant system latency or performance degradation may be automatically disabled by the system.
- Centralized Insights: New health monitoring dashboards will be available in the Microsoft Purview compliance portal, providing visibility into classifier performance and flagging “unhealthy” configurations.
- Data Integrity: Simulation runs on production data to ensure accuracy, but because the classifier is not yet “published,” it does not alter actual data classification outcomes or end-user experiences during the test phase.
Action Required
- Review Development Lifecycle: Update internal compliance procedures to include a “Simulation Phase” for all new custom classifiers to ensure logic is sound before wide-scale deployment.
- Monitor Health Insights: Once the feature rolls out in March 2026, navigate to the Purview compliance portal to review the health status of existing custom SITs.
- Remediation: If a classifier is flagged as “unhealthy” or “inefficient,” proactively adjust the logic or regex patterns to prevent the classifier from being automatically disabled for performance reasons.
- Access Control: Verify that relevant IT personnel have the necessary role-based permissions in Entra ID to access Purview simulation and monitoring tools.
Microsoft Official Update
Service: N/A
Category: stayInformed
Severity: normal
Updated February 4, 2026: We have updated the timeline. Thank you for your patience.
[Introduction]
Microsoft Purview is introducing Classifier Simulation Mode, the first phase of the broader Classifier Health Monitoring Platform. This new capability allows admins to test and validate custom classifiers on production data before publishing. Simulation Mode enables admins to optimize classifier logic before deployment, helping in reducing false positives, scanning latency, and noisy matches. Admins will access simulation controls and classifier health insights directly in the Microsoft Purview compliance portal, making it easier to monitor and improve classifier performance in one centralized location.
This message is associated with Roadmap ID 523201.
[When this will happen:]
- Public Preview: Rollout begins early March 2026 (previously early November 2025), completes by mid-April 2026 (previously early December 2025).
- General Availability (Worldwide): Rollout begins late May 2026 (previously late February), completes by late May 2026 (previously late March).
[How this affects your organization:]
- Who is affected: Admins managing Microsoft Purview Information Protection and custom sensitive information types (SITs).
- What will happen:
- By default, the feature will be available to all tenants.
- Admins will see a new option to simulate a custom classifier before publishing.
- Simulation is optional — admins can choose to simulate or publish directly.
- Classifiers published without simulation will still be monitored for performance and flagged if unhealthy.
- Classifier health insights will be available in the Microsoft Purview compliance portal, helping admins identify and remediate inefficient classifiers.
- Inefficient classifiers may be automatically disabled to maintain system performance.
[What you can do to prepare:]
- Admins can begin using Simulation Mode once available; no onboarding or training is required.
- Once the feature is available:
- Review classifier health insights in the compliance portal.
- Monitor any SITs flagged as unhealthy and adjust logic as needed.
- Consider simulating classifiers before publishing to reduce risk of false positives or performance issues.
[Compliance considerations:]
| Question | Explanation |
|---|---|
| Does the change alter how existing customer data is processed, stored, or accessed? | Classifiers will be simulated on production data, but not published, allowing analysis without altering data classification outcomes. |
| Does the change introduce or significantly modify AI/ML or agent capabilities that interact with or provide access to customer data? | Introduces classifier health monitoring logic that evaluates classifier performance and flags inefficiencies. |
| Does the change modify how admins can monitor, report on, or demonstrate compliance activities? | Adds new health insights and monitoring capabilities for custom classifiers in the compliance portal. |
| Does the change include an admin control and, can it be controlled through Entra ID group membership? | Simulation and publishing options are available to admins; access can be managed via role-based permissions. |
