SPF Record Analyzer
Resolve and analyze the SPF record for any domain - including recursive include chains, DNS lookup counting, and policy violation detection.
v=spf1 a:www939.sakura.ne.jp a:www2278.sakura.ne.jp mx ~all
Violations (1)
Mechanisms (4)
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About this tool
SPF (Sender Policy Framework) is a DNS TXT record that lists which servers are authorized to send email on behalf of a domain. Receiving mail servers check this record against the sender's IP - if the IP isn't listed, the email can be rejected or flagged as spam.
The most critical part of the SPF record is the catch-all mechanism at the end: -all (hard fail, reject unlisted senders), ~all (soft fail, mark but accept), ?all (neutral, no effect), or +all (pass all senders - effectively disables SPF). For strong spam protection, always end with -all.
RFC 7208 limits SPF evaluation to 10 DNS lookups. The include:, a, mx, ptr, exists, and redirect= mechanisms each count as one lookup. Going over the limit causes a PermError, which means receiving servers will treat the email as if SPF failed - even though the sending IP might be legitimately authorized.
SPF alone is not enough. For full email authentication, combine SPF with DKIM signing and a DMARC policy. Without DMARC, a passing SPF check can still be bypassed using the display name while sending from a different domain.
