Microsoft Endpoint DLP relies on Microsoft Defender for Endpoint (MDE) for its enforcement.
Onboarding Windows 10/11 devices to Defender for Endpoint ensures the Endpoint DLP policies can be applied, including monitoring and protecting content across apps and browsers.
Reference: Overview of Endpoint DLP

Explanation:

Explanation:

Activity Explorer logs a DLP rule match event each time any DLP rule condition is met on a file.
File1 matches Rule11 and Rule12 # 2 events
File2 matches Rule21 and Rule22 # 2 events
File3 matches Rule11 and Rule22 # 2 events
Total events in Activity Explorer = 2 + 2 + 2 = 6.
Microsoft notes that Activity explorer shows granular DLP activities such as policy rule matches per item.
The DLP incidents report aggregates by policy match per item, not by each rule in that policy. Multiple rules from the same policy on the same item count as one incident; if different policies match the same item, each policy creates its own incident.
File1: Rules from DLP1 only # 1 incident
File2: Rules from DLP2 only # 1 incident
File3: One rule from DLP1 and one from DLP2 # 2 incidents
Total incidents = 1 + 1 + 2 = 4.
References: Microsoft Purview DLP explains that Activity explorer records detailed DLP activities, while DLP incidents are created when a policy match occurs for an item, and multiple rule matches within a single policy are consolidated into a single incident for that item.

Comprehensive Detailed Explanation with References
Step 1 - Review File2 contents
File2 contains 3 IP addresses.
Step 2 - Review DLP rules and priorities
RuleConditionPolicy TipStop Processing?Priority
Rule11 or more IP addressesTip1No0
Rule23 or more IP addressesTip2Yes1
Rule32 or more IP addressesTip3No2
Step 3 - Rule evaluation order
Advanced DLP rules are processed by priority order (lowest number first).
Rule1 (Priority 0) will trigger because File2 has at least 1 IP address.
This applies Tip1.
However, Rule1 has Stop Processing = No, so evaluation continues.
Rule2 (Priority 1) will also trigger because File2 has 3 IP addresses (#3).
This applies Tip2.
Rule2 has Stop Processing = Yes, so evaluation stops after this.
Rule3 (Priority 2) will not be evaluated because Rule2 stopped processing.
Step 4 - Final outcome
File2 matches Rule1 (Tip1), but since Rule2 fires afterward with Stop Processing = Yes, only Tip2 is applied.
Step 5 - Microsoft Reference
From Microsoft docs: "When a rule is configured to stop processing, subsequent rules are not evaluated and only the policy tip from the last triggered rule with stop processing applies." Reference: Order of rule processing in DLP policies

Step 1 - Scenario
Tenant domain = contoso.com
Encryption method = Microsoft Purview Advanced Message Encryption (AME) using branded, link-based emails.
Recipients:
Recipient1 # Contoso internal user (same tenant).
Recipient2 # External Microsoft 365 user (Fabrikam).
Recipient3 # Outlook.com consumer email.
Recipient4 # Gmail.com consumer email.
The question asks: For which recipients can User1 revoke the emails?
Step 2 - Revocation in Advanced Message Encryption
Microsoft Purview AME allows senders to:
Revoke sent encrypted emails.
Revoke applies to all recipients who receive a link-based branded encrypted message.
When revoked, the secure message link no longer works, regardless of whether the recipient is internal, external Microsoft 365, Outlook.com, Gmail, or another email provider.
This differs from traditional RMS-based encryption where revocation is tenant-specific. In AME, the revocation is possible because the recipient must open the message through a secure browser portal (Office
365 Message Encryption portal).
Step 3 - Evaluate each recipient
Recipient1 (contoso.com, internal) # Yes, message can be revoked.
Recipient2 (fabrikam.onmicrosoft.com, external Microsoft 365) # Yes, message can be revoked because AME link enforcement works across tenants.
Recipient3 (outlook.com, consumer) # Yes, message can be revoked, they use the secure OME portal.
Recipient4 (gmail.com, consumer) # Yes, message can be revoked, they also use the secure OME portal.
Step 4 - Microsoft Reference
From Microsoft Docs:
"With Advanced Message Encryption, admins can configure branding and revocation for encrypted email messages. Revocation applies to encrypted emails sent to both internal and external recipients, including those using Outlook.com, Gmail.com, and other email services." Reference: Microsoft Purview Advanced Message Encryption