Glossary
Email authentication
Void lookup
A DNS query during SPF evaluation that returns NXDOMAIN or an empty answer. More than two void lookups is a permerror — a separate limit from the ten-lookup one, in the same section, and very widely missed.
Defined in RFC 7208 §4.6.4.
Where this appears
The lessons that use this term, and what each is for.
Email Authentication FundamentalsThe limits that break SPFCount a record against both RFC 7208 limits and say which one it will hit first.SPF PractitionerCounting, with the working shownProduce a defensible lookup count for any record, including every nested include.SPF PractitionerFinding the void lookupsLocate every void lookup in a record tree and say which term produced it.SPF PractitionerTracing a permerror to its termName the exact term that produced a permerror, not merely that one occurred.SPF PractitionerHow a correct record stops being correctName what you would monitor so a record does not fail without anyone noticing.