Email deliverability in modern enterprise environments depends entirely on cryptographic sender verification. Major mailbox providers (Google, Yahoo, Microsoft) enforce strict SPF, DKIM, and DMARC alignment for all high-volume senders.
1. The Three Pillars of Email Authentication
| Protocol | DNS Record Type | Cryptographic Mechanism | Deliverability Impact |
|---|---|---|---|
| SPF (Sender Policy Framework) | TXT | Validates sending MTA IP addresses against domain policy | Prevents unauthorized IP spoofing |
| DKIM (DomainKeys Identified Mail) | TXT / CNAME | Asymmetric 2048-bit RSA cryptographic signature in email headers | Verifies body & header integrity in transit |
| DMARC (Domain-based Message Auth) | TXT (_dmarc) | Specifies alignment enforcement (none, quarantine, reject) | Stops domain impersonation & phishing |
🔐 DMARC Alignment Best Practice
Deploy v=DMARC1; p=reject; rua=mailto:dmarc-reports@emailcampaigner.info; pct=100; adkim=s; aspf=s; to mandate 100% strict alignment and prevent spoofed phishing attacks.