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SPF Record (Strict)

Same as the SPF Record check, plus verifies the record uses an enforcing policy. SPF supports four "all" qualifiers:

QualifierMeaningStrict check
-allHard fail (reject unauthorized IPs)passes
~allSoft fail (mark as suspicious)passes
?allNeutral (no policy)fails
+allPass everything (effectively no SPF)fails
missingImplicit ?allfails

A ?all policy provides no enforcement value to receivers, which is usually a configuration mistake. Use this check on domains where you want to enforce that SPF actually does something.

Applies to: URIBL and URI hosts.

How It Works

Same lookup as the basic SPF Record check, with one extra step: we walk the SPF tokens looking for the all mechanism and verify the qualifier.

When the record uses redirect=, we follow the redirect target's SPF (up to 5 levels with cycle detection) and check its all qualifier instead. This is necessary because many SaaS senders delegate SPF management via redirect=.

Fails On

  • No SPF record found.
  • More than one SPF record found.
  • No all mechanism in the record (or its redirect target).
  • all qualifier is ? (neutral) or + (pass-everything).
  • redirect= chain has a cycle.
  • SPF Record - basic version that accepts any policy.
  • SPF Lookup Limit - verifies the SPF record stays under RFC 7208's 10-DNS-lookup cap.