SPF Checker

Check a domain's SPF record — syntax, multiple-record conflicts, and common misconfigurations.

About this tool

SPF (Sender Policy Framework) lists which mail servers are authorized to send email for a domain. This tool fetches the domain's SPF record, checks it's syntactically valid, confirms there's exactly one (RFC 7208 requires this — having more than one causes SPF to fail entirely), and flags common misconfigurations.

What gets checked

  • Multiple SPF records — a domain must publish exactly one; more than one causes a permanent SPF failure for every mail server that checks it.
  • The 10-lookup limit — SPF mechanisms like include, a, and mx each consume a DNS lookup, capped at 10 by RFC 7208. Exceeding it causes a permanent error.
  • An "all" mechanism — defines what happens for senders matching nothing else. +all specifically is almost always an unintentional, serious misconfiguration.

Related tools:

DKIM Checker DMARC Checker MX Checker Email Security Checker