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SPF

Sender Policy Framework — authorizes hosts that may send for a domain.

Reading time:: 5 min
Difficulty:: Intermediate
Estimated duration:: 5 min
Prerequisites:: DNS, TXT records
Last updated:: 2026-07-15
Author:: empire

Definition

Sender Policy Framework — authorizes hosts that may send for a domain.

Prerequisites

DNSDomain Name System — the lookup fabric email authentication depends on.
TXT recordsDNS record type used for SPF, DMARC, and many auth artifacts.

DNSDomain Name System — the lookup fabric email authentication depends on.
TXT recordsDNS record type used for SPF, DMARC, and many auth artifacts.
AuthenticationIdentity signals for email: SPF, DKIM, DMARC, and related controls.
DKIMDomainKeys Identified Mail — cryptographic signatures for message integrity.
DMARCDomain-based Message Authentication, Reporting, and Conformance.

Broken SPF includeAn included SPF domain is missing, invalid, or fails closed.
Forwarded email fails SPFForwarding paths break SPF because the forwarder is not authorized.
Incorrect IP authorizationSending infrastructure IPs are not authorized by SPF.
Invalid SPF mechanismSPF record contains unsupported or malformed mechanisms.
Multiple SPF recordsMore than one SPF TXT record exists, causing evaluation failure.
SPF passes but DMARC failsSPF authenticates a domain that does not align for DMARC.
SPF PermErrorSPF evaluation fails permanently due to policy or lookup errors.
SPF record missingNo SPF TXT record is published for the sending domain.
SPF TempErrorTemporary DNS or evaluation failure during SPF checks.
Too many DNS lookupsSPF evaluation exceeds the ten-lookup limit.

digCLI DNS lookup utility for authoritative and recursive inspection of mail-related records.
MXToolboxPopular DNS and mail diagnostics suite for SPF, DMARC, blacklist, and MX checks.
Mail-TesterSend-a-message spam and authentication scoring for pre-send QA.
Kitterman SPF validatorClassic web SPF policy evaluator used by operators for syntax checks.

Open step-by-step: Configure SPFPublish and validate an SPF policy for authorized senders.
Open step-by-step: Migrate authentication recordsMove SPF, DKIM, and DMARC to a new platform without dual-record failures.

Empire Services

SPF, DKIM, and DMARC implementationHands-on implementation of core authentication records and signing.

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