Service details

Email and Domain Mail Checks

Check one email address or domain for common syntax and published mail configuration

0.002 USDC per completed check

Paid only. No free trial for this operation.

Use this service →

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Know its boundaries.

Mailbox existence or message deliverability verification
SMTP probes or test email
Exhaustive disposable-domain classification
SPF evaluation for a specific sender or automatic DKIM selector discovery
Inherited organizational-domain DMARC policy

Data handling

The address or domain is processed in memory and never written to application telemetry. DNS lookups reveal the queried domain to the configured resolver.

Input example and exact contract

{
  "kind": "domain",
  "value": "example.org"
}

API reference: input, output and error schemas →

Example output

{
  "service": "email-domain-checks",
  "schema_version": "1",
  "domain": "example.org",
  "syntax": "not_applicable",
  "mail_route": {
    "status": "mx_configured",
    "mx": {
      "status": "ok",
      "values": [
        [
          10,
          "mail.example.org"
        ]
      ],
      "ttl_seconds": 60
    }
  },
  "spf": {
    "status": "record_found",
    "record": "v=spf1 -all",
    "dns": {
      "status": "ok",
      "ttl_seconds": 60
    }
  },
  "dmarc": {
    "status": "record_found",
    "record": "v=DMARC1; p=reject",
    "dns": {
      "status": "ok",
      "ttl_seconds": 60
    }
  },
  "dkim": {
    "status": "selector_required"
  },
  "disposable": "not_on_small_known_list",
  "mailbox_exists": "unknown"
}

Calling, result interpretation and recovery

Calling

Endpoint: POST /v1/email/domains/check-mail-configuration
Content type: application/json
Input: kind=email or domain; value is one address or domain. Optional selector checks one DKIM TXT name.

Interpret the result

Syntax: valid_common_form does not establish mailbox existence.
Mail route: mx_configured and address_fallback identify possible routes, not acceptance. Null MX means no mail.
Spf: Record presence at the queried name only; not a sender authentication result.
Dmarc: Record presence at the exact queried name only; inherited policy is not assessed.
Disposable: A small known-list match only.
Mailbox exists: Always unknown.
Dkim: Without a selector, selector_required. A supplied selector checks only that DNS name; record presence does not validate a signature.

Limits

Request bytes

1024

Semantics

One input per request. No batch.
Common dot-atom syntax only; unsupported valid forms are marked unsupported_form.
DNS timeouts remain unknown; a total DNS outage is uncharged.
DNS TTL bounded to 300 seconds in process.
DKIM selectors may have period-separated labels; no guessing or scanning.

Payment and recovery

Price

0.002 native USDC per completed check

Network

Solana mainnet or Base mainnet

Protocol

x402 v2 exact

Quote

Send the intended JSON body without PAYMENT-SIGNATURE. A 402 PAYMENT-REQUIRED header contains two network offers; bodyless preflight is not payable.

Authorization

Choose one accepts entry with a standard x402 v2 client. Check native USDC, network, recipient, amount and intended input before signing. Solana uses an SVM transaction; Base uses an EOA EIP-3009 authorization (USD Coin version 2). Send the proof with identical JSON input. No API key, token approval, bridge or Solana wallet is needed for Base. Never automatically fall back to another network.

Retry

Retry the identical body and original proof after an ambiguous response. A full DNS outage is uncharged.

Finality

A finalized response independently checks chain success and the exact transfer. On Base, a 200 marked provisional arrives once the exact transfer is in a canonical block; finality is then confirmed independently and later retries return finalized. A 202 remains pending. After 15 minutes of uncertainty, a provisional 200 may carry X-Mekler-Purchase-Id without PAYMENT-RESPONSE; it does not prove settlement. Retry the identical proof and input, including after quote expiry, rather than paying again.

Expiry

Ongoing service under recurring monthly authority. Budget warnings do not stop service. Short-lived quotes and recovery retention still expire.

Networks

solana:5eykt4UsFv8P8NJdTREpY1vzqKqZKvdp
eip155:8453

Assets

Solana:5eykt4usfv8p8njdtrepy1vzqkqzkvdp: EPjFWdd5AufqSSqeM2qN1xzybapC8G4wEGGkZwyTDt1v
Eip155:8453: 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913

Fees

CDP sponsors the payment transaction gas on both networks. The service price is the same on either network; wallet funding or exchange fees are separate.

Request binding

The server authenticates the complete quote and input and atomically binds the first accepted authorization to them. Standard Base EIP-3009 signs the money terms and nonce, not HTTP content. Keep signatures private; do not reuse an authorization for another quote, operation or body.