Definition
Email authentication is a set of standards that verify an email genuinely came from the sender it claims to be from, and that it was not tampered with. The core protocols are SPF, DKIM and DMARC.
SPF lists the servers allowed to send mail for your domain. DKIM signs your email with a cryptographic signature that recipients can verify. DMARC ties SPF and DKIM together and tells providers what to do when an email fails checks.
Authentication matters for deliverability and security: providers trust authenticated senders more, and it protects your brand from spoofing. Implement all three, monitor reports, and align your SPF/DKIM with your DMARC policy.
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Related Glossary Terms
Email Authentication Protocols
Email authentication protocols are technical standards that verify the identity of an email sender, helping mailbox providers distinguish legitimate mail from spam and phishing.
BIMI
BIMI (Brand Indicators for Message Identification) is an email standard that allows brands to display their logo next to their emails in supported email clients. It requires DMARC enforcement at quarantine or reject policy.
DKIM (DomainKeys Identified Mail)
DKIM (DomainKeys Identified Mail) is an email authentication method that uses digital signatures to verify that an email was not tampered with during transit and comes from a authorised domain.
DMARC Alignment
DMARC identifier alignment determines whether the domain in the From header matches the domains used in SPF and DKIM authentication. Strict or relaxed.
DMARC Policy Tags
DMARC DNS record tags including v, p, sp, rua, ruf, pct, adkim, aspf, fo, rf, and ri control authentication policy, reporting, and alignment enforcement.
DMARC (Domain-based Message Authentication)
DMARC (Domain-based Message Authentication, Reporting and Conformance) is an email authentication protocol that builds on SPF and DKIM to prevent domain spoofing and provide reporting on authentication failures.
Frequently Asked Questions
It is using standards like SPF, DKIM and DMARC to prove an email genuinely came from the claimed sender, which improves deliverability and blocks spoofing.
SPF lists authorized sending servers, DKIM cryptographically signs your mail, and DMARC tells providers how to handle messages that fail those checks.
Yes. Mailbox providers use authentication as a core trust signal, and unauthenticated or failing mail is far more likely to be filtered, rejected or marked suspicious.