Audit email security DNS records (SPF, DMARC, MX, CAA)
Audit email security DNS records (SPF, DMARC, MX, CAA). Evaluates RFC 7208 SPF 10-lookup limits, DMARC policy enforcement strength, identifies mail providers, and computes a security score
Request
- x-api-key: <your-api-key>
- Content-Type: application/json
Response
{
"auditSummary": {
"auditTimestamp": "2026-09-08T10:00:00Z",
"domain": "example.com",
"totalIssuesFound": 38
},
"caaAudit": {
"authorizedCAs": [
"<authorized ca>"
],
"hasCaa": true
},
"deliverabilityStatus": "EXCELLENT",
"dmarcAudit": {
"adkim": "<adkim>",
"aspf": "<aspf>",
"hasDmarc": true,
"issues": [
"<issue>"
],
"percentage": 42,
"policy": "<policy>",
"rawRecord": "<raw record>",
"rua": "<rua>",
"ruf": "<ruf>",
"subdomainPolicy": "<subdomain policy>"
},
"mxAudit": {
"hasMx": true,
"mailProvider": "castomapi",
"records": [
{
"exchange": "<exchange>",
"priority": 12
}
]
},
"securityScore": 0,
"spfAudit": {
"exceedsLookupLimit": true,
"hasSpf": true,
"issues": [
"<issue>"
],
"lookupCount": 3,
"policyQualifier": "<policy qualifier>",
"rawRecord": "<raw record>"
},
"status": "success",
"tokensDeducted": 2
}What it does
Audit email security DNS records (SPF, DMARC, MX, CAA). Evaluates RFC 7208 SPF 10-lookup limits, DMARC policy enforcement strength, identifies mail providers, and computes a security score
Request
Body
| Field | Type | Required | Description |
|---|---|---|---|
domain | string | yes | Target root domain name to audit (e.g. "github.com" or "stripe.com") |
Example request
{
"domain": "example.com"
}Response
| Field | Type | Description |
|---|---|---|
auditSummary | object | |
↳ auditTimestamp | string | |
↳ domain | string | |
↳ totalIssuesFound | integer | |
caaAudit | object | |
↳ authorizedCAs | array<string> | |
↳ hasCaa | boolean | |
deliverabilityStatus | enum | One of: EXCELLENT, GOOD, VULNERABLE, CRITICAL_RISK. |
dmarcAudit | object | |
↳ adkim | string | |
↳ aspf | string | |
↳ hasDmarc | boolean | |
↳ issues | array<string> | |
↳ percentage | integer | |
↳ policy | string | |
↳ rawRecord | string | |
↳ rua | string | |
↳ ruf | string | |
↳ subdomainPolicy | string | |
mxAudit | object | |
↳ hasMx | boolean | |
↳ mailProvider | string | |
↳ records | array<object> | |
securityScore | integer | |
spfAudit | object | |
↳ exceedsLookupLimit | boolean | |
↳ hasSpf | boolean | |
↳ issues | array<string> | |
↳ lookupCount | integer | |
↳ policyQualifier | string | |
↳ rawRecord | string | |
status | string | |
tokensDeducted | integer |
Example response
{
"auditSummary": {
"auditTimestamp": "2026-09-08T10:00:00Z",
"domain": "example.com",
"totalIssuesFound": 38
},
"caaAudit": {
"authorizedCAs": [
"<authorized ca>"
],
"hasCaa": true
},
"deliverabilityStatus": "EXCELLENT",
"dmarcAudit": {
"adkim": "<adkim>",
"aspf": "<aspf>",
"hasDmarc": true,
"issues": [
"<issue>"
],
"percentage": 42,
"policy": "<policy>",
"rawRecord": "<raw record>",
"rua": "<rua>",
"ruf": "<ruf>",
"subdomainPolicy": "<subdomain policy>"
},
"mxAudit": {
"hasMx": true,
"mailProvider": "castomapi",
"records": [
{
"exchange": "<exchange>",
"priority": 12
}
]
},
"securityScore": 0,
"spfAudit": {
"exceedsLookupLimit": true,
"hasSpf": true,
"issues": [
"<issue>"
],
"lookupCount": 3,
"policyQualifier": "<policy qualifier>",
"rawRecord": "<raw record>"
},
"status": "success",
"tokensDeducted": 2
}Errors
Every error answers with the same envelope: an HTTP status, a machine code and a sentence.
400 | The body or a parameter failed validation. The details array names the field. |
401 | No key, a revoked key or a wrong header. Send x-api-key. |
402 | The wallet cannot cover this call. Top up or wait for the monthly grant. |
404 | The resource does not exist, or it is not yours. Both answer identically and cost nothing. |
429 | Over the per-minute quota of your tier. Back off and retry. |
5xx | Upstream refused or timed out. The call is not billed. |
Code
curl -X POST 'https://app.castomapi.com/v1/verify/email-dns' \
-H 'x-api-key: <your-api-key>' \
-H 'Content-Type: application/json' \
-d '{"domain": "example.com"}'const res = await fetch('https://app.castomapi.com/v1/verify/email-dns', {
method: 'POST',
headers: { 'x-api-key': '<your-api-key>', 'Content-Type': 'application/json' },
body: JSON.stringify({"domain": "example.com"})
});
const data = await res.json();
console.log(data);import { request } from 'node:https';
// Node 18+ has fetch built in
const res = await fetch('https://app.castomapi.com/v1/verify/email-dns', {
method: 'POST',
headers: { 'x-api-key': '<your-api-key>', 'Content-Type': 'application/json' },
body: JSON.stringify({"domain": "example.com"})
});
const data = await res.json();
console.log(data);import requests
res = requests.post(
'https://app.castomapi.com/v1/verify/email-dns',
headers={'x-api-key': '<your-api-key>'},
json={"domain": "example.com"},
timeout=30,
)
print(res.json())<?php
$ch = curl_init('https://app.castomapi.com/v1/verify/email-dns');
curl_setopt_array($ch, [
CURLOPT_CUSTOMREQUEST => 'POST',
CURLOPT_RETURNTRANSFER => true,
CURLOPT_HTTPHEADER => ['x-api-key: <your-api-key>', 'Content-Type: application/json'],
CURLOPT_POSTFIELDS => json_encode(['domain' => 'example.com']),
]);
$data = json_decode(curl_exec($ch), true);
print_r($data);Cost and limits
This operation costs 2 tokens. A call that fails is never billed. Every account gets 1000 free tokens a month; paid balances never expire.
Rate limits per minute
| No key | 10 |
| Free | 60 |
| Pro | 300 |
| Enterprise | 1200 |
Questions
What does Audit email security DNS records (SPF, DMARC, MX, CAA) cost?
2 tokens per successful call, debited from your wallet after the response. Failed calls are free. Every account receives 1000 free tokens a month.
How do I authenticate?
Send your key in the x-api-key header. One key covers every metered endpoint; there is nothing to enable per endpoint.
Can I send an Authorization: Bearer token instead?
Not for a metered endpoint — those take the x-api-key header and nothing else. Bearer tokens belong to the account side: the dashboard and account APIs accept a JWT session, and castomapi-auth issues those through a standard OAuth2 handshake, with authorization code, client credentials and refresh grants. The auth service page covers it.
What are the limits?
10 requests a minute per IP with no key at all, 60 a minute on the free tier, 300 on Pro, 1200 on Enterprise. Above the no-key tier the quota is per account, across every endpoint.
OpenAPI: https://app.castomapi.com/docs/json