# SPF Record IP Evaluator (Literal Mechanisms Only)

> 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.

## Facts

- Endpoint: POST https://emailauth.openverbs.com/v1/spf-check
- Price: $0.004/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-13
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/spf-record-ip-evaluator-literal-mechanisms-only-c04b7c12
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_kkquMw7Rgu9jyyyvDPNud

Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently.

## How to call it through Zero

Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`):

```sh
zero fetch --capability spf-record-ip-evaluator-literal-mechanisms-only-c04b7c12 -d '<json body>'
```

Example prompt: Check whether the IP 203.0.113.42 is authorized by this SPF record: 'v=spf1 ip4:203.0.113.0/24 ip6:2001:db8::/32 -all' — I only want a result based on the literal ip4/ip6/all mechanisms, no DNS lookups.

## When to prefer this

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.

## Known failure modes

- 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

## 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.

## Request schema (JSON Schema)

```json
{
 "$schema": "https://json-schema.org/draft/2020-12/schema",
 "type": "object",
 "properties": {
  "input": {
   "type": "object",
   "properties": {
    "type": {
     "type": "string",
     "const": "http"
    },
    "method": {
     "type": "string",
     "enum": [
      "POST"
     ]
    },
    "bodyType": {
     "type": "string",
     "enum": [
      "json",
      "form-data",
      "text"
     ]
    },
    "body": {
     "type": "object",
     "properties": {
      "record": {
       "type": "string",
       "description": "SPF TXT record to evaluate."
      },
      "ip": {
       "type": "string",
       "minLength": 1,
       "description": "IPv4 or IPv6 address of the sending host."
      }
     },
     "required": [
      "record",
      "ip"
     ],
     "additionalProperties": false
    }
   },
   "required": [
    "type",
    "method",
    "bodyType",
    "body"
   ],
   "additionalProperties": false
  }
 },
 "required": [
  "input"
 ]
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/spf-record-ip-evaluator-literal-mechanisms-only-c04b7c12/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from emailauth.openverbs.com](https://www.zero.xyz/host/emailauth.openverbs.com/llms.txt)