SPFDKIMDMARC

SPFDKIMDMARC refers to the coordinated use of three email authentication techniques—SPF, DKIM, and DMARC—to verify that messages originate from legitimate domains and to provide reporting on authentication results. It is not a single protocol, but a layered strategy aimed at reducing spoofing and improving deliverability.

SPF, or Sender Policy Framework, allows a domain owner to publish a list of authorized sending hosts in a DNS TXT record. When a mail server receives a message, it can check the MAIL FROM domain against the SPF record. SPF has limitations, including forwarders breaking the check and the need to manage DNS lookups, which are capped in most implementations.

DKIM, DomainKeys Identified Mail, adds a cryptographic signature to messages. The signature is created by the sending domain and verified via a public key published in DNS. DKIM preserves message integrity in transit, but alignment with the visible From address is optional depending on policy and selector usage.

DMARC, Domain-based Message Authentication, Reporting & Conformance, ties SPF and DKIM results to the domain in the From header and specifies a policy for handling failures (none, quarantine, or reject). DMARC also enables reporting, so domain owners can monitor who sends on their behalf.

Implementation typically starts with publishing SPF, enabling DKIM signing, and configuring DMARC in a reporting mode (p=none). Over time, operators may move to stricter policies (p=quarantine or reject) as confidence grows, while reviewing aggregate and forensic reports to adjust records and avoid false positives.

See also: SPF, DKIM, DMARC.