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SPF

published · September 13, 2026

SPF (Sender Policy Framework, RFC 7208) is a DNS TXT record in which a domain lists the servers allowed to send mail using its name, ending in a qualifier that says what to do with the rest.

SPF, the Sender Policy Framework of RFC 7208, is a DNS TXT record beginning v=spf1 in which a domain lists the addresses, hosts and included policies allowed to send mail using its name, and ends with an all term whose qualifier — -all fail, ~all soft fail, ?all neutral — says what a receiver should make of everything else. A receiver evaluates it against the envelope sender of each message.

What Spaw answers

An email answer carries has_spf; a business domain without a record adds the no_spf weight of 10, while free providers are exempt because theirs is known. The domain endpoint adds spf_all, the effective qualifier, and spf_lookup_count, the number of DNS-querying terms the policy needs once include: and redirect= are followed — RFC 7208 allows ten, and a policy over that limit fails permanently at every receiver, which is the most common SPF fault there is.

What it does not mean

SPF says who may send as the domain's envelope sender. It says nothing about the address a person sees in their mail client, which is what DKIM alignment and DMARC cover, and it breaks on forwarding, which is why a -all policy is not by itself a reason to expect delivery.

Related

markdown version: /glossary/spf.md

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More glossary

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  • Number portability

    Number portability lets a subscriber keep a phone number when changing carrier. The number's block stays listed under the carrier it was issued to, so block data names the original holder.