Layer Breakdown
Layer 1: RFC 5322 Syntax Standard
Strict grammar verification parsing local-parts, domain labels, punycode, unquoted spaces, quotes, and length limits.
Layer 2: DNS & TLD Viability
Asynchronous DNS queries verifying root nameservers, authoritative SOA, and A/AAAA address records.
Layer 3: Authoritative MX Routing
Discovers Mail Exchanger priority records and tests for RFC 7505 Null MX dead domain configurations.
Layer 4: Direct Port 25 SMTP Ping
Opens direct TCP socket to remote mail server, executing HELO, MAIL FROM, and RCPT TO dialogue without transmitting message bodies.
Layer 5: 100K+ Burner Disposable Firewall
In-memory Radix Trie matching incoming domains against 100,000+ known temporary, disposable, and 10-minute mail providers.
Layer 6: Catch-All Fingerprinting
Probes randomized mailbox aliases to detect domains configured to blindly accept all mail.
Layer 7: Spam Trap & Threat Defense
Cross-references target domains against honeypot heuristics and spam trap footprints to protect domain reputation.