Email Security Protocols Guide [2026]
Plain-language guides to email authentication protocols. Learn DMARC, SPF, DKIM, BIMI, MTA-STS, TLS-RPT, DANE, ARC, and ARF.
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 guideSPF Record Syntax: Format, Examples & Mechanisms [2026]
Learn SPF record syntax, format, and mechanisms. Understand how Sender Policy Framework works, common errors like PermError, and the 10-lookup limit.
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 (Authenticated Received Chain, RFC 8617) preserves email authentication through forwarding and mailing lists. Learn how ARC-Seal, ARC-Message-Signature, and ARC-Authentication-Results work — and how ARC fixes DMARC failures.
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 what DANE is, how TLSA records work, DANE vs MTA-STS, and how to set up SMTP DANE (RFC 6698).
Read guideBrand & Reporting
Protocols for brand display in inboxes and standardized abuse reporting.
What Is BIMI? Record Setup & DNS Examples [2026]
BIMI displays your brand logo in the inbox once you reach DMARC enforcement. Learn what a BIMI record is, how to create one, VMC requirements, and which email clients support BIMI.
Read guideWhat Is ARF? Abuse Reporting Format (RFC 5965) [2026]
ARF (Abuse Reporting Format, RFC 5965) is the format behind DMARC failure reports (RFC 9991) and feedback-loop complaints. Learn what ARF is, what an ARF file contains, and how to read one.
Read guideCompliance
Industry standards that mandate email authentication for regulatory compliance.
Want practical tips and troubleshooting walkthroughs? Browse our email security blog.
Put these protocols to work for your domains
DMARCguard monitors all 10 protocols continuously, parses incoming reports, and gives you actionable steps to reach full compliance.
Start Free