The rule titled "O365 Email Send Attachments Excessive Volume" aims to detect potentially malicious behavior associated with Office 365 email accounts. Specifically, it identifies instances where an account sends an excessive number of email attachments to external recipients within a one-hour timeframe. Such behavior may point to a compromised email account being exploited for data exfiltration. The analytics leverage the Office 365 Universal Audit Log, focusing on delivered messages and correlating them with management activities like sending emails. The rule filters out common attachment types (like images) to zero in on more suspicious file transfers. If an account exceeds a threshold of 25 attachments in the specified period, an alert is triggered, which could be legitimate or indicative of nefarious activity. The implementation requires the Splunk Microsoft Office 365 Add-on to ingest necessary logs, and it accounts for potential false positives related to legitimate usage patterns. Users should adjust thresholds based on their operational context.