Email Bombing - High Volume Inbound or Inbox Deletion Rule

This rule detects two suspicious activities within a user's mailbox: (1) An email flood, where a recipient receives more than 500 emails within a 5-minute window, potentially indicating an attempt to overwhelm or hide secondary emails; and (2) The creation or modification of inbox rules that include actions like deleting or moving messages, which is a common persistence and evasion technique used by attackers to hide C2 or phishing communications.