SPF Flattening

SPF records can only trigger 10 DNS lookups before mail fails with a PermError. Check a domain's live lookup count and see whether it's at risk — the first step to flattening an over-stuffed record.

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Why flatten SPF?

Stay under the 10-lookup ceiling.

Every include:, a, mx and redirect in your SPF triggers a DNS lookup. Past ten, strict receivers throw a PermError and your SPF fails — flattening replaces those lookups with raw IP ranges.

  1. 01

    Count your lookups

    Enter a domain and we tally exactly how many DNS-lookup mechanisms its SPF record uses, live.

  2. 02

    See your headroom

    A clear gauge shows where you sit against the limit of 10 — healthy, near, or already over.

  3. 03

    Know what to flatten

    We list the exact include: mechanisms costing you lookups, so you know which ones to replace with ip4/ip6 ranges.

FAQ

SPF flattening, answered.

include, a, mx, ptr, exists and redirect each cost one or more DNS lookups when SPF is evaluated. ip4 and ip6 mechanisms cost nothing — which is why flattening converts includes into raw IP ranges.
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