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SPF Record IP Evaluator (Literal Mechanisms Only)
x402
SPF Record IP Evaluator (Literal Mechanisms Only) is a paid API for AI agents from emailauth.openverbs.com, paid per call via x402, $0.004/call, status unknown (last checked 2026-09-13).
Evaluates an SPF TXT record against a sending IP address using only literal ip4/ip6/all mechanisms, returning indeterminate for DNS-dependent mechanisms encountered before a match.
Price / call$0.004
Success—
StatusUnknown
How this service works
Evaluate an SPF record against an IPv4/IPv6 address using only its literal ip4/ip6/all mechanisms. DNS-dependent mechanisms (include, a, mx, exists, redirect) reached before a match yield an honest `indeterminate` result rather than a guess.
Output
Returns the SPF evaluation outcome for the provided IP against the given SPF record's literal mechanisms (ip4, ip6, all). Possible results include pass, fail, softfail, neutral, or indeterminate — where indeterminate is returned honestly when a DNS-dependent mechanism (include, a, mx, exists, redirect) is encountered before a literal match is found, rather than guessing.
Example use cases
Validate outbound mail server IP
“I have an SPF record 'v=spf1 ip4:198.51.100.0/24 -all' — can you check if the IP 198.51.100.15 would pass it using only the literal mechanisms?”
Detect unauthorized sender IP
“An email came in from 192.0.2.77 — evaluate it against the SPF record 'v=spf1 ip4:10.0.0.0/8 ip6:fe80::/10 ~all' and tell me if it's a match, fail, or indeterminate.”
Pre-deployment SPF policy sanity check
“Before I publish my SPF record 'v=spf1 ip4:203.0.113.5 ip4:203.0.113.6 -all', can you verify that 203.0.113.5 passes and 1.2.3.4 fails using only the literal ip4 and all mechanisms?”
Technical details
Endpoint
POSThttps://emailauth.openverbs.com/v1/spf-checkWhen to prefer
Choose this endpoint when you need a fast, deterministic SPF check against literal ip4/ip6/all mechanisms without triggering DNS lookups — ideal for offline analysis, pre-deployment validation, sandbox environments, or when you explicitly want to isolate literal mechanism evaluation. Unlike full SPF validators, it is honest about DNS-dependent mechanisms by returning 'indeterminate' rather than making network calls or guessing, making it safe for constrained or air-gapped contexts.
Side effects
- Missing required 'record' or 'ip' field returns a 400-level error
- Malformed SPF record string may cause a parse error or unexpected result
- DNS-dependent mechanisms encountered before any literal match yield 'indeterminate' rather than an error
- Invalid IP address format returns a validation error
- Empty or non-SPF record strings may not evaluate correctly
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| inputrequired | object |
Tags
x402
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