Retention policy tags (MRM) for Exchange Online are applied by the Managed Folder Assistant (MFA). To apply a newly created Exchange retention policy to mailbox items immediately, you manually invoke MFA with Start-ManagedFolderAssistant for the mailbox or set of mailboxes. Creating DLP policies or label policies in Purview does not accelerate MRM processing.

Explanation:

Microsoft Purview browser extensions for Endpoint DLP are supported on:
# Windows 10/11 (Config1)
# macOS (Config2)
# Not supported on Android (Config3)
Since Microsoft Purview does not support browser extensions on Android, Config3 is excluded from both Google Chrome and Firefox.

Endpoint DLP builds on Microsoft Defender for Endpoint integration. Before enabling Endpoint DLP, you must turn on device onboarding in Microsoft Purview to allow devices (like Device1) to be enrolled. After onboarding, you can assign DLP policies to endpoints.
Reference: Get started with Endpoint DLP

Explanation:

Policy1 monitors printing of files by users that submitted their resignation. In Insider Risk Management, the Data theft by departing users template is designed for users marked as leaving and watches for exfiltration indicators such as printing, USB copy, or uploads to cloud services.
Ref: Microsoft Purview Insider Risk Management - Policy templates: Data theft by departing users (monitors exfiltration activities for departing users).
Policy2 monitors accidental sharing of data outside the organization by users in a priority user group. The template for this is Data leaks by priority users, which targets a defined priority user group and focuses on oversharing/leak indicators (external sharing, email to external, cloud uploads, etc.).
Ref: Insider Risk Management - Data leaks by priority users template.
Policy3 monitors downloading of files from SharePoint Online to personal cloud storage services. This is a classic data leak/exfiltration scenario without a departing/priority qualifier, so the general Data leaks template is appropriate (covers uploads to personal cloud services and other exfiltration vectors).
Ref: Insider Risk Management - Data leaks template (monitors exfiltration such as uploads to personal cloud services).
These mappings align with Microsoft's template purposes: Departing user exfiltration # Data theft by departing users; Priority users oversharing # Data leaks by priority users; Generic exfiltration # Data leaks.

To implement Microsoft Purview Data Lifecycle Management for SharePoint Online (Site1), you need to create a retention label first. Retention labels define how long content should be retained or deleted based on compliance requirements. Once a retention label is created, it can be manually or automatically applied to content in SharePoint Online, Exchange, OneDrive, and Teams. After creating a retention label, you can configure label policies to apply them to Site1 and other locations.