What is SPF? (Email glossary definition)

SPF (Sender Policy Framework) is an email authentication mechanism defined in RFC 7208. It works through DNS. Domain owners publish a TXT record listing every IP address or hostname authorized to send mail from their domain. Receiving servers check this record on every inbound message and reject or mark as suspicious any mail from a sender not in the list.

A typical SPF record looks like:

v=spf1 include:_spf.google.com include:sendgrid.net ~all

SPF is one of three layers in the modern email-authentication stack, alongside DKIM and DMARC. All three are now effectively required for bulk senders to reach Gmail and Yahoo inboxes.

Common gotchas: max 10 DNS lookups per record, only one SPF record per domain, and ~all (softfail) vs -all (hardfail) controls whether non-matching mail is marked or rejected.

See what is an SPF record for the full guide and how to set up SPF for the setup walkthrough. Free SPF checker on our site.