This rule is designed to detect emails that originate from sender domains using Punycode, which is a method for encoding internationalized domain names (IDN). Punycode can be exploited by threat actors to create deceptive domains that visually resemble legitimate domains, thereby facilitating phishing attacks and other credential theft efforts. The presence of "xn--" in the sender's email domain is a strong indicator of a potential impersonation attempt. This detection rule focuses on inbound emails, analyzing the sender's domain for the specific Punycode pattern. By identifying such domains, organizations can mitigate risks associated with credential phishing, malware distribution, and social engineering attacks.