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    Authentication

    DMARC

    A policy you publish in DNS that tells inbox providers what to do if SPF or DKIM checks fail.

    DMARC (Domain-based Message Authentication, Reporting & Conformance) lets you set a policy of none, quarantine, or reject. It also delivers regular reports showing who is sending email using your domain. Gmail and Yahoo now require at least a DMARC policy of p=none for senders mailing 5,000+ recipients per day. Most ESPs walk you through DMARC setup as part of their deliverability tools.

    Related terms

    SPF (Sender Policy Framework)

    A DNS record that lists which servers are allowed to send email on behalf of your domain.

    DKIM (DomainKeys Identified Mail)

    A cryptographic signature added to outgoing emails that proves the message really came from your domain and was not tampered with.