What is an SPF record?

An SPF record is a TXT record starting with v=spf1 that lists which servers are authorized to send email for a domain. Receiving servers check the connecting server's IP against the record's mechanisms and pass or fail the message accordingly.

What is the difference between -all, ~all, and +all?

The all mechanism ends the record and sets the default. -all (hardfail) tells receivers to reject mail from unlisted servers. ~all (softfail) is weaker: unlisted senders are marked suspicious but often still delivered. +all passes every sender, which defeats the purpose of SPF entirely.

What is the SPF 10 lookup limit?

RFC 7208 caps the DNS lookups an SPF check may perform at 10. The include, a, mx, ptr, exists, and redirect terms each cost one lookup, and nested includes count too. Past 10, receivers return permerror and the record stops protecting the domain.

Check any domain's SPF record

See which servers a domain authorizes to send its email, and whether the record holds up.

What you get

Mechanisms parsed

Every include, ip4, ip6, a, mx, exists, and redirect term is listed as its own row, so you can read the policy without decoding the raw string.

All qualifier explained

The record's -all, ~all, ?all, or +all ending is graded, since +all lets anyone pass SPF and softfail is weaker than hardfail.

Lookup count checked

DNS-querying terms are counted against the RFC 7208 limit of 10, past which receivers return permerror and stop evaluating the record.

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Check any domain's SPF record

Mechanisms parsed

All qualifier explained

Lookup count checked

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