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SPF checker

/spf

Validate your SPF record and count its DNS lookups against the limit of 10.

Read live from public DNS. Nothing is stored.

What SPF does

  1. What it is

    SPF is a public list of the servers allowed to send email for your domain.

  2. Why it matters

    Receivers check the sending server against your list. On the list, it passes.

  3. Without it

    Without SPF, anyone can send mail claiming to be your domain and receivers have no way to tell.

What we check

  • That your domain publishes exactly one valid v=spf1 record
  • Every mechanism, and which ones cost a DNS lookup
  • The number of DNS-lookup mechanisms against SPF's hard limit of 10
  • Your all qualifier, and whether it actually protects you

Common questions

How many DNS lookups is too many?

SPF allows a maximum of 10 DNS-lookup mechanisms (include, a, mx, ptr, exists and redirect). Go over, and receivers return a PermError and may fail your mail.

What's the difference between ~all and -all?

-all (hard fail) tells receivers to reject anything not listed. ~all (soft fail) tells them to accept but mark it. Neither +all nor ?all gives you real protection.