Microsoft Purview | Data Loss Prevention- DLP to restrict processing external emails in M365 Copilot and Copilot Chat

Microsoft Purview is adding a new Data Loss Prevention (DLP) control for Microsoft 365 Copilot and Copilot Chat to exclude external emails from being used as grounding data in AI responses. This feature, off by default, will roll out from June to August 2026 and requires admin configuration. We’re expanding Microsoft Purview Data Loss Prevention (DLP) controls for Microsoft 365 Copilot and Copilot Chat to help organizations reduce the risk of untrusted or externally sourced content influencing AI‑generated responses. This new capability allows admins to exclude emails from external senders from being used as grounding data during Copilot prompt processing. When enabled, Copilot continues to generate responses using trusted internal Microsoft 365 data sources, subject to existing licensing and policy controls. This message is associated with Microsoft 365 Roadmap ID 548671. When this will happen Public preview: We will begin rolling out in early June 2026 and expect to complete by late June 2026. General availability (Worldwide): We will begin rolling out in late July 2026 and expect to complete by late August 2026. How this affects your organization Who is affected Organizations using Microsoft 365 Copilot (Premium) or Copilot Chat Admins managing AI governance, security, and data protection using Microsoft Purview What will happen A new DLP policy control will be available for Microsoft 365 Copilot and Copilot Chat. When enabled by an admin: Emails sent from external or untrusted domains are excluded from being: Referenced Summarized Used as grounding data by Copilot Copilot continues to generate responses using trusted internal Microsoft 365 data sources (for example, SharePoint, OneDrive, and internal Exchange content), subject to existing licensing and policy. This change does not: Affect email delivery, retention, eDiscovery, or user access Change existing Copilot interaction behavior unless the policy is explicitly configured Default state: Off by default. There is no change unless an admin enables this control in Microsoft Purview. Screenshot 1. Select Microsoft 365 Copilot and Copilot Chat as the DLP policy location:  View image in new tab Screenshot 2. New DLP setting to restrict processing of external email content:  View image in new tab What you can do to prepare […]

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