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MailCheck Domain Check API
x402
MailCheck Domain Check API is a paid API for AI agents from mailcheck.toolschemaforge.workers.dev, paid per call via x402, $0.001/call, status unknown (last checked 2026-10-31).
Checks one or more domains for DNS records, mail infrastructure health (SPF/DMARC/DKIM), RDAP registration data, and returns a deliverability grade
Price / call$0.001
Success—
StatusUnknown
How this service works
Email address and domain checks for AI agents: syntax, MX, disposable/role/free flags, typo suggestions, SPF/DMARC/DKIM, RDAP and a deliverability grade. Pay per item with x402 (USDC on Base) or Lightning sats. No signup.
Output
Returns a JSON object with a count and an array of per-domain results. Each result includes: input domain, validity flag, deliverability grade (A–F), numeric score, reasons array, DNS records (A, AAAA, MX, NS, TXT), mail config (accepts_mail, null_mx, parsed SPF, parsed DMARC, DKIM selectors found), and RDAP registration data (registrar, created/updated/expires dates, age_days, days_to_expiry, statuses, nameservers, DNSSEC).
Example use cases
Pre-send domain deliverability audit
“Before we launch our email campaign, check deliverability for sendgrid.com and mailgun.com — I need to know their SPF and DMARC status and whether they'd get a good deliverability grade.”
Verify domain mail security posture
“Can you audit the email security setup for stripe.com? I want to see whether they have SPF, DMARC with a reject policy, and any DKIM selectors configured.”
Domain registration and expiry check
“Look up the registration details for notion.so — when was it created, when does it expire, who's the registrar, and is it in good standing?”
Technical details
Endpoint
GEThttps://mailcheck.toolschemaforge.workers.dev/v1/domain-check?utm_source=zero.xyzWhen to prefer
Choose this endpoint when you need comprehensive domain-level email infrastructure analysis in a single call — combining DNS, SPF/DMARC/DKIM, RDAP registration, and a deliverability grade — without signup or subscriptions, paying only per domain checked. Prefer it over general DNS lookup tools when you need the full mail security picture, or over WHOIS tools when you also need deliverability scoring.
Side effects
- Invalid or malformed domain input returns valid:false with reasons
- Domain not found in DNS returns exists:false
- RDAP lookup may return null if registry does not support RDAP
- DKIM selector discovery may return empty array if no selectors found
- Payment failure (x402/Lightning) blocks the request before processing
- Rate limiting or network timeouts from upstream DNS/RDAP resolvers
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| inputrequired | object | |
| output | object |
Output
Schema · Response
{
"type": "json",
"example": {
"count": 1,
"results": [
{
"mail": {
"spf": {
"all": "-all",
"present": true
},
"dkim": {
"found": []
},
"dmarc": {
"policy": "reject",
"present": true
},
"null_mx": true,
"accepts_mail": false
},
"grade": "A",
"input": "example.org",
"score": 100,
"valid": true,
"domain": "example.org",
"exists": true,
"reasons": [
"null MX: domain declares it sends/receives no mail"
],
"registration": {
"status": "ok",
"created": "1995-08-31T04:00:00Z",
"expires": "2027-08-30T04:00:00Z",
"registrar": "Example Registrar"
}
}
]
}
}Tags
x402
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