SPF's 10-Lookup Limit: Includes, Flattening, and Permerror
Every include, a, mx, and redirect in your SPF record costs a DNS lookup, and the budget is ten. Why records break at scale and how to fix them without flattening regret.
#Permerror
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SPF Records Demystified: Why Your "v=spf1" Setup Is Probably Wrong
Most SPF records are subtly broken. The 10-lookup limit, multiple records, +all, and the alignment trap what's actually wrong with your SPF setup.