How do we get started with Microsoft Purview data loss prevention?

Key facts

• DLP policies run in simulation mode first so you can measure matches before blocking anything.
• Sensitive information types and trainable classifiers identify the data; policies decide what happens.
• Policy tips teach users in the moment and reduce help desk friction.
• Licensing determines which locations you can cover, so check it before designing policies.
• Most failed DLP rollouts try to protect everything at once.

Decide what you are protecting

DLP works best when it targets specific data with a clear business reason. Start by asking which leaks would cause real harm: regulated personal data, financial account details, health information, or confidential client and deal documents.

Purview includes many built-in sensitive information types, such as US Social Security numbers, credit card numbers and bank account numbers, plus templates for common regulations. For your own data, you can create custom types using keywords and patterns, use exact data match for structured records, or rely on sensitivity labels that users or auto-labeling apply.

Check licensing and locations

Purview DLP can cover Exchange Online, SharePoint Online, OneDrive, Teams chat and channel messages, Windows and macOS endpoints, and some on-premises and third-party locations. Which ones you can use depends on licensing.

Business Premium and Microsoft 365 E3 include DLP for core email and file locations. Teams chat DLP, Endpoint DLP and some advanced features generally need E5-level compliance licensing or add-ons. Confirm current entitlements in Microsoft's service descriptions before promising coverage to stakeholders.

Build the first policies in simulation

Create each policy in simulation mode. Purview shows how many items match and where, without affecting users. Leave it running long enough to see normal business patterns, typically two to four weeks.

• Scope the first policy to Exchange, SharePoint and OneDrive.
• Use a high-confidence condition, such as several card numbers or SSNs in one item, to limit noise.
• Target external sharing first; internal sharing of sensitive data is often normal.
• Review matches in Activity explorer and the simulation dashboard.
• Identify legitimate business processes that trigger matches, such as payroll or benefits teams.

Tune, then enforce in stages

Tuning is where most of the work is. Raise instance counts, adjust confidence levels, add exceptions for approved recipients or groups, and refine custom types. Each change should reduce false positives without hiding real risk.

Then enforce in steps. First, turn on policy tips and notifications so users see a warning. Next, block with an option for users to override with a business justification. Finally, block outright for the highest-risk scenarios. Review override reasons; they show where the policy or the process needs work.

Run DLP as an ongoing program

Decide who reviews DLP alerts and how quickly. Route high-severity alerts to the Defender or Purview alert queue and set up incident reports for owners of the affected data.

Test that policies keep detecting what they should. Seed known test content periodically, confirm alerts fire, and check that policies still cover new SharePoint sites and Teams. Review the policy set each quarter alongside sensitivity labels and retention, since the three work together.

How Accred Consulting approaches it

Accred Consulting starts DLP with discovery: which data matters, where it lives, which licenses you have and who will review alerts. The proposal sets a clear scope, pricing and timeline for a first set of policies. US-based specialists build them in simulation, review matches with your data owners, tune false positives and enforce in stages with policy tips and structured check-ins. Accred configures the Microsoft 365 controls that support your compliance program; your organization and its assessor own compliance. Handover includes documentation and knowledge transfer, with optional support retainers for ongoing tuning.

Track record: 475+ client projects, 2,000+ migration workstreams and 210,000+ users migrated by a US-based team. Company facts · Case studies

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