Email notifications for triggered Transaction Security policies include more detail. In addition to the policy name and events that triggered the policy, you now see the policy’s ID and related org ID and user ID. More information helps you identify affected orgs and streamline investigations.
Where: This change applies to Enterprise, Performance, Unlimited, and Developer editions.
Who: This change is available to customers who purchased Salesforce Shield or Salesforce Event Monitoring add-on subscriptions.
Get More Informative Transaction Security Policy Notifications (salesforce.com)