How Microsoft Purview Works: Architecture, Data Governance, and Best Practices

Introduction

Microsoft Purview is more than a compliance add-on—it is Microsoft’s full-fledged data governance and compliance platform. While our Purview Buyer’s Guide focused on whether Purview is the right compliance investment, this post explains how it actually works.

For IT managers and technical staff, understanding Purview’s architecture, data governance model, and networking configuration is critical to running it efficiently. We’ll also explore best practices gathered from Microsoft documentation, Tech Community discussions, and administrator experiences.

Inside the Purview Data Map

The Data Map is the metadata backbone of Microsoft Purview. It discovers, catalogs, and classifies information from supported Microsoft 365 sources and connected systems, enabling consistent governance and search across the estate. Purview scans services like Exchange Online, SharePoint, OneDrive, and Teams to collect metadata, build lineage, and apply classifications that downstream policies can act on.

• Discovery: Purview automatically scans supported sources (Exchange, SharePoint, OneDrive, Teams) to collect metadata.
• Classification: Built-in and custom classifiers label sensitive information such as financial data, source code, or health records.
• Governance: Metadata from the Data Map feeds into policies for retention, DLP, and insider risk.

The Data Map feeds the Purview Catalog, which gives administrators and reviewers a searchable inventory of data assets—critical for retention, eDiscovery, DLP, and audit scenarios. This design ensures that compliance rules are applied at the metadata level, giving organizations both flexibility and defensibility during audits.

Domains, Collections, and Role-Based Access

In large enterprises, one of the biggest risks in governance platforms is configuration sprawl—policies scattered across dozens of admin accounts, without clear ownership. Microsoft Purview’s domains and collections model, combined with role-based access control (RBAC), provides structure that scales.

• Domains represent broad areas of the business, such as Finance, HR, or Legal.
• Collections allow further segmentation within domains—for example, a Finance domain might include collections for Payroll, Treasury, and Auditing.

This structure has two main advantages:

• Policy Application at Scale – IT teams can apply retention and compliance policies to collections rather than configuring them individually.
• Delegated Administration – Using role-based access control (RBAC), Purview allows collection-level permissions. This lets global IT maintain oversight while business-unit IT admins manage their own areas.

Domains and collections aren’t optional—they’re the scaffolding that makes Purview manageable in enterprise environments. Combined with RBAC, they enable scalable governance and defensible audit trails.

Guidance: Best practices for domains and collections and Purview permissions.

Connections and Data Ingestion

Microsoft Purview is a metadata-driven system. It does not copy full content into its Data Map—instead, it ingests metadata (schemas, classifications, sensitivity info) and links back to the source system. This keeps storage and performance overhead lower, but it also means Purview is only as powerful as the sources it can connect to. Purview connects to data sources in two main ways:

• Built-in Microsoft 365 connectors – Exchange Online, SharePoint, OneDrive, Teams, and Viva Engage.
• External connectors – Through APIs and Microsoft’s partner ecosystem, Purview can integrate with on-premises SQL servers, data warehouses, and some SaaS platforms.

Purview ingestion is strongest inside Microsoft 365, but IT managers must plan for hybrid and multi-channel sources. Without external archiving integrations, compliance visibility will stop at the Microsoft boundary. While Purview integrates natively with Microsoft workloads, capturing non-Microsoft channels (Slack, WhatsApp, Bloomberg, SMS) requires a third-party solution. For many organizations, this is where Intradyn Archiving becomes the essential complement.

Networking: Public vs Private Endpoints

Networking is a critical part of any Purview deployment because it determines how the service communicates with your environment and where the traffic flows. By default, Purview relies on public internet endpoints, but Microsoft also supports private networking models for organizations that require stricter isolation. Understanding the difference between public and private endpoints is key to aligning your Purview deployment with security and compliance requirements. Purview’s architecture runs on Azure and provides two networking options:

• Public Endpoints (default) – Quick to deploy, accessible via Microsoft’s global infrastructure.
• Private Endpoints – Allow you to restrict Purview traffic to your private Azure Virtual Network. This is recommended for organizations with strict firewall rules or regulated environments requiring network isolation.

Public endpoints are quick and simple, but private endpoints are essential for organizations under heavy regulatory scrutiny. While they require more Azure networking expertise, they significantly improve compliance defensibility and reduce external attack exposure.

Automation and APIs

Managing Microsoft Purview entirely through the portal can become time-consuming as environments grow. To help IT teams scale operations and maintain consistency, Microsoft provides multiple automation options. Through PowerShell modules, REST APIs, and event-driven integrations, Purview tasks like provisioning, policy deployment, and catalog updates can be scripted and orchestrated, reducing manual effort and minimizing configuration drift. Running Purview manually does not scale. Microsoft supports automation through:

• PowerShell / Az.Purview module – Provision archive mailboxes, deploy retention labels, and manage policies at scale.
• REST APIs – Control scanning, classifications, and catalog updates programmatically.
• Event Hubs & Apache Atlas – Subscribe to entity change events (e.g., new classification applied) and trigger workflows like alerts or catalog refreshes.

Example: an IT team can script automatic scanning of new SharePoint sites and alert compliance staff if sensitive data is detected.

Data Classification and Sensitive Data Insights

At the heart of Microsoft Purview’s governance capabilities is its ability to classify and label sensitive information. By automatically detecting data types—from credit card numbers to healthcare identifiers—Purview enables IT and compliance teams to understand where sensitive data resides, how it moves, and whether it is adequately protected. These insights form the basis for applying retention policies, enforcing DLP rules, and demonstrating compliance during audits. Purview’s governance engine includes a classification system designed to identify sensitive data across the environment.

• Pre-trained classifiers detect common data types such as credit card numbers, social security numbers, or healthcare identifiers.
• Custom trainable classifiers can be trained on your organization’s documents, such as proprietary contract templates or internal coding standards.
• Sensitive data insights appear in dashboards, giving IT managers a view of where data is stored, how it’s being shared, and whether DLP rules are working.

This functionality is critical for compliance with GDPR, HIPAA, PCI DSS, and other frameworks.

Best Practices from the Field

Running Microsoft Purview effectively requires more than just enabling features—it demands careful planning and operational discipline. Insights shared by administrators in the Microsoft Tech Community highlight recurring themes: monitoring capacity, staging exports, networking choices, governance delegation, and automation. Together, these practices help IT teams avoid unnecessary costs, reduce risk, and improve compliance outcomes.

Monitor Capacity Units in the Data Map

Purview charges by capacity units (CUs) for scanning and governance operations. These units measure the processing of metadata ingestion and classification. If left unchecked, CU overages can escalate costs quickly. IT managers should set up monitoring and alerts to track CU consumption, especially in environments with heavy scanning or frequent schema changes.

Stage eDiscovery Exports

Export performance is one of Purview’s most frequently cited pain points. Microsoft enforces a 2 TB/day export limit per tenant, meaning very large cases can stall if handled in a single batch. A proven approach is to split exports by custodian or by date range. Many administrators also schedule exports overnight to minimize contention with production workloads.

Use Private Endpoints for Sensitive Data

Organizations in finance, healthcare, and government often deploy Purview with private endpoints. Although setup requires additional configuration—DNS updates, firewall rules, and Azure VNet planning—the benefits include a reduced attack surface and simplified regulatory attestations. For sensitive workloads, this tradeoff is worth the added effort.

Delegate via Collections, Not User Groups

Purview’s role-based access control (RBAC) model is most effective when tied to collections rather than user groups. Assigning permissions at the collection level provides clarity, reduces overlap, and avoids conflicts caused by nested or overlapping groups. This structure also makes audit reviews more defensible, since responsibilities are clearly mapped to organizational units.

Automate Routine Tasks

Manual administration does not scale. By leveraging PowerShell or REST APIs, IT teams can automate recurring tasks such as provisioning archive mailboxes, rotating retention policies, or triggering compliance scans when new data sources are onboarded. Automation reduces administrative burden, enforces consistency, and lowers the risk of configuration drift in fast-changing environments.

Comparison: Purview vs Third-Party Governance Solutions

While Purview is strong within Microsoft 365, gaps remain in: