Self-Hosted Email Threat Detection: Real-Time Monitoring, Multi-Stage Enrichment, and LLM Verdicts with Legal Compliance

Introduction: The Escalating Email Threat Landscape and the Imperative for Self-Hosted Solutions Email remains the cornerstone of organizational communication, yet it constitutes a critical vulnerability in cybersecurity infrastructure. The exponential proliferation of email-based attacks —including phishing, malware, and spoofing—has transformed inboxes into primary vectors for cyber exploitation. Traditional defense mechanisms are increasingly ineffective against polymorphic threats , which evolve faster than signature-based detection systems can adapt. Concurrently, third-party email security providers introduce a critical vulnerability : their operational model necessitates access to sensitive data, creating a centralized risk for privacy breaches. The self-hosted email threat detection system represents a paradigm shift, addressing both technical and ethical deficiencies. By integrating IMAP IDLE for real-time monitoring , multi-stage enrichment (SPF/DKIM/DMARC/DNSBL/WHOIS/URLhaus