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    SPF Lookup Limit Calculator

    Recursively expand your SPF record and count every DNS lookup against the RFC 7208 10-lookup limit.

    Calculate SPF DNS lookups

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    What is the SPF 10-lookup limit?

    RFC 7208 §4.6.4 limits SPF evaluation to 10 DNS lookups. The limit covers the entire recursive chain — every include:,redirect=,a,mx,exists:, andptr across all nested records. Exceed it and receivers return permerror, which fails SPF for every message.

    A parallel cap limits void lookups (NXDOMAIN / empty answers) to 2.

    What this calculator does

    • Fetches your domain's TXT records and finds the v=spf1 record
    • Recursively expands every include: and redirect=
    • Tallies the total lookup count across the whole chain
    • Counts void lookups against the 2-void limit
    • Renders the full lookup tree so you can see exactly which branch is heavy

    How to reduce SPF lookups

    • Remove include: entries for services you no longer use
    • Replace heavy includes with their published ip4: / ip6: ranges where the vendor allows it
    • Consolidate subdomains under one record where possible
    • Use a hosted SPF flattening service if your include chain is unavoidable
    • Drop deprecated ptr mechanisms entirely

    Frequently asked questions

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    Go beyond one-off checks

    Safer Sender continuously monitors your domain's DMARC, SPF and DKIM, classifies every sender, and guides you safely from p=none to p=reject.

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