12 Microsoft 365 Security Features and Best Practice Guidance – 8: Data Loss Prevention (DLP) for Email and Files

What is it?

Microsoft 365 Data Loss Prevention (DLP) is a powerful set of tools designed to help organisations detect and prevent the accidental or unauthorised sharing of sensitive information via email and file storage services like SharePoint Online and OneDrive for Business.

DLP policies can automatically scan messages, attachments and stored documents for patterns that match confidential data types such as credit card numbers, NHS numbers, National Insurance numbers, or personal health information, and take appropriate action to protect it.

Whether you're working in finance, healthcare, legal, or any other data-sensitive sector, DLP ensures your organisation stays compliant and your information stays protected.

Why is this important?

• Prevents accidental or intentional sharing of sensitive data

• Supports compliance with regulations such as GDPR, ISO 27001, and PCI-DSS

• Helps avoid data breaches and reputational damage

• Gives users helpful prompts before they send risky content

• Monitors and controls file sharing across SharePoint and OneDrive

Data protection isn’t just a legal requirement, it’s a trust issue. DLP helps you maintain control over your data, keeping your staff and customers safe.

Where is it included?

DLP capabilities are included in various Microsoft 365 and Office 365 plans depending on the level of protection required:

• Microsoft 365 E3: Includes core DLP features across Exchange Online, SharePoint Online, and OneDrive for Business.

• Microsoft 365 E5: Adds advanced DLP capabilities including integration with Microsoft Defender for Cloud Apps, policy tuning with analytics, and enhanced reporting.

• Microsoft Purview Compliance Suite: DLP is also part of Microsoft Purview, offering centralised policy management, advanced auditing, and data classification.

Depending on your current licensing, you might already have access to these features or could benefit from an upgrade for advanced capabilities.

Real world scenario

One of our legal sector clients was regularly handling sensitive case documents via email and SharePoint. They had concerns around unauthorised data sharing, especially with increased hybrid working.

Through our Microsoft 365 Security Service, HybrIT:

• Identified key data types (e.g. case reference numbers, client financials)

• Built tailored DLP policies for Exchange, SharePoint and OneDrive

• Applied user education policies – warning messages before emails with risky content were sent

• Integrated alerts and incident logging into Microsoft Purview

• Reviewed sharing permissions on SharePoint sites and locked down external sharing

The result? A clear reduction in policy violations, increased user awareness around data sensitivity, and full auditability to support their compliance and risk management strategy.

Best practice tips

• Start small – roll out DLP in audit mode first to observe patterns before enforcing restrictions

• Use built-in templates – Microsoft offers pre-configured rules for GDPR, financial data and more

• Combine with sensitivity labels – apply encryption and access control to sensitive files

• Enable user notifications – educate users with policy tips in Outlook and Teams

• Monitor and tune policies – refine based on what you’re seeing in the DLP reports

• Restrict file sharing – limit access to authorised users and trusted domains

• Integrate with Microsoft Defender – extend DLP to cloud apps and endpoints

DLP Feature Availability

Here’s a quick guide showing where Microsoft DLP applies across different Microsoft 365 services:

✅ Yes – fully supported ❌ No – not applicable or not currently supported

How HybrIT can help configure this

At HybrIT, we’ve worked with organisations across healthcare, education, professional services and beyond to build robust, intelligent DLP strategies using Microsoft 365.

Whether you’re looking to meet compliance obligations, improve internal data handling practices, or reduce your exposure to accidental data loss, our team can help by:

• Identifying your key sensitive data and risks

• Creating and testing custom and built-in DLP policies

• Rolling out user-friendly policy tips and training

• Integrating DLP with Defender and other Purview tools

• Providing ongoing monitoring and policy tuning support

• Helping with audit readiness and incident investigations

We take a hands-on approach that’s tailored to your business and your regulatory environment, ensuring your DLP strategy is practical, manageable, and effective.

Let’s talk about how we can help protect your sensitive information, reduce your risk, and build user confidence in the process.

📞 Call us on 03330 156 702📧 Email hello@hybrit.co.uk