Cold email glossary

What is Email authentication?

The set of DNS-based checks — SPF, DKIM and DMARC — that let a receiving server verify an email really came from the domain it claims.

Authentication is the entry ticket to the inbox. Without it a receiver has no way to distinguish your mail from a spoof, and since 2024 Gmail, Yahoo and (from 2025) Microsoft require it. SPF authorises sending servers, DKIM signs messages, DMARC ties both to the visible From domain and sets a policy. All three take about twenty minutes to set up on a hosted mailbox provider.

Related terms

GlossarySPFSender Policy Framework — a DNS TXT record listing which servers may send email for your domain.GlossaryDKIMDomainKeys Identified Mail — a cryptographic signature your mail provider adds to each message, verified against a public key published in your DNS.GlossaryDMARCA DNS policy record that tells receivers what to do when SPF and DKIM fail or don't align with the From domain, and asks them to send you reports.

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