Email Security Protocols Guide [2026]
Plain-language guides to email authentication protocols. Learn DMARC, SPF, DKIM, BIMI, MTA-STS, TLS-RPT, DANE, ARC, ARF, and APRF.
Email Authentication
Protocols that verify sender identity and protect against spoofing.
DMARC Email Auth Guide [2026]
Learn how DMARC protects your domain from email spoofing. Covers DMARC records, policies (none/quarantine/reject), alignment, reporting, and SPF/DKIM.
Read guideWhat Is SPF? How It Works, Provider Setup & Alignment [2026]
How SPF works, how to set it up for Google Workspace and Microsoft 365, how SPF alignment feeds DMARC, and how to fix common failures.
Read guideWhat is DKIM? How DKIM Signatures & Records Work [2026]
DKIM adds cryptographic signatures to emails, verifying sender identity and message integrity. Learn how it works, record examples, and key rotation.
Read guideWhat Is ARC? Authenticated Received Chain [2026]
ARC (RFC 8617) carries authentication results across forwarding and mailing lists. How it works, who honors it, and the draft to make it Historic.
Read guideTransport Security
Protocols that encrypt email in transit and prevent downgrade attacks.
TLS-RPT SMTP TLS Reporting [2026]
TLS-RPT (RFC 8460) monitors SMTP TLS failures between mail servers. Learn how to set up your DNS record, read reports, and fix errors.
Read guideWhat Is MTA-STS? DNS Record & Policy File [2026]
Learn what MTA-STS is, how it prevents TLS downgrade attacks, and how to set up your DNS record and policy file. RFC 8461 guide with provider examples.
Read guideWhat Is DANE? TLSA Records & SMTP DANE [2026]
DANE binds your mail server's TLS certificate to DNS with DNSSEC and TLSA records. Learn how TLSA records work, DANE vs MTA-STS, and SMTP DANE setup.
Read guideBrand & Reporting
Protocols for brand display in inboxes, abuse reporting and inbox placement reporting.
What Is BIMI? Record Setup & DNS Examples [2026]
BIMI puts your brand logo in the inbox once you reach DMARC enforcement. Learn how to create a BIMI record, VMC requirements, and which clients support BIMI.
Read guideAbuse Reporting Format (ARF) for Email (RFC 5965) [2026]
ARF (Abuse Reporting Format, RFC 5965) is the format behind DMARC failure reports and feedback-loop complaints — and how to read one.
Read guideAPRF: Aggregate Performance Reporting for Email [2026]
APRF (Aggregate Performance Reporting), an IETF draft: mailbox providers send DKIM signers daily placement and engagement reports. Record, format, setup.
Read guideCompliance
Industry standards that mandate email authentication for regulatory compliance.
Client-Side Security
Browser-enforced protections that guard the pages users land on.
Want practical tips and troubleshooting walkthroughs? Browse our email security blog.
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