This detection rule focuses on identifying brand impersonation attempts targeting Mailgun, an email delivery platform. The rule measures various sender characteristics and message content for indicators of potential impersonation. It assesses if certain elements in the sender's email, subject, and message body exhibit similarities to Mailgun's branding, such as the display name or email domains that may mimic legitimate Mailgun addresses. Key markers include inspecting the presence of the term 'mailgun' in various forms, parsed using regex for robustness against typographical errors, and monitoring for specific HTML titles or logos that may signal spoofing. The rule also negates high-trust identifiers unless DMARC (Domain-based Message Authentication, Reporting & Conformance) checks fail, maximizing accuracy by reducing false positives. The rule is intended for medium severity detections, indicating that while these impersonation attempts can be harmful, they require further analysis after triggering.