How much does a email-validate call cost?

$0.002 per call, paid in USDC on Base via x402, with no account and no API key.

What does email-validate return?

A JSON object with 7 top-level fields: email, valid, syntax_valid, mx_found, mx_records, is_disposable and is_role_account. The example on this page is a real call.

What happens when a email-validate call fails?

The tool answers with a typed JSON error from the errors table. Payment is settled only after the tool has produced its result; a call that fails inside the tool is never settled. A 503 upstream_unavailable can follow a settled call; the x402 payments guide covers it, 429, 402 and an uncertain 500.

catalogue / tools / Domain, DNS & network / Email Validate API

Email Validate API

Validates an email address: syntax, MX records for its domain, and whether it is a disposable or role account.

Endpoint: POST /v1/email-validate
Price: $0.002 per call
Family: Domain, DNS & network
Docs: /docs/email-validate

01When to use it

The MX check needs a resolver an agent may not have, and the disposable/role assessment is a curated dataset and rule set it would otherwise have to build and keep current.

When not to use it

The destination needs more than 5 s to answer: the call ends with upstream_timeout (424).

02Parameters

Field	Type	Required	Description
email	string	yes	The address to assess, up to 320 characters; it is trimmed, and a malformed address is answered with syntax_valid false rather than rejected.
check_mx	boolean	no	Whether to resolve MX records for the domain; when true, a domain with no MX makes valid false, and false skips every network lookup. Default: true.
check_disposable	boolean	no	Whether to match the domain against the bundled disposable-provider list; when true, a disposable domain makes valid false. Default: true.

03Limits

Limit	Value
Size cap	2 MB (2,097,152 bytes)
Timeout	5 s

04Example

The published example of email-validate, verbatim: the request body and the response it returns.

Request

POST /v1/email-validate
content-type: application/json
payment-signature: <base64 x402 payload>

{
  "email": "[email protected]",
  "check_mx": false
}

Response

200 OK
payment-response: <base64 settlement receipt>

{
  "email": "[email protected]",
  "valid": true,
  "syntax_valid": true,
  "mx_found": false,
  "mx_records": [],
  "is_disposable": false,
  "is_role_account": true
}

Response field	Type	In the example
email	string	"[email protected]"
valid	boolean	true
syntax_valid	boolean	true
mx_found	boolean	false
mx_records	array	0 items
is_disposable	boolean	false
is_role_account	boolean	true

05Call it from code

JavaScript

// email-validate: $0.002 per call, paid in USD Coin on eip155:8453 via x402
// Install: npm install @x402/fetch@2 @x402/evm@2 viem@2
// Save as client.mjs (ES module, Node 18+), export EVM_PRIVATE_KEY with the paying wallet's key in your shell, then run: node client.mjs
// The wrapper reads the 402 (payment-required), signs and retries with payment-signature.
import { wrapFetchWithPayment, x402Client, decodePaymentResponseHeader } from '@x402/fetch'
import { ExactEvmScheme } from '@x402/evm/exact/client'
import { privateKeyToAccount } from 'viem/accounts'

const account = privateKeyToAccount(process.env.EVM_PRIVATE_KEY)
const client = new x402Client().register('eip155:8453', new ExactEvmScheme(account))
const fetchWithPayment = wrapFetchWithPayment(fetch, client)

const body = {
  "email": "[email protected]",
  "check_mx": false
}

const res = await fetchWithPayment('https://grist.tools/v1/email-validate', {
  method: 'POST',
  headers: { 'content-type': 'application/json' },
  body: JSON.stringify(body),
})
console.log(res.status, await res.json())
const settle = res.headers.get('payment-response')
if (settle) console.log(decodePaymentResponseHeader(settle).transaction)

Python

# email-validate: $0.002 per call, paid in USD Coin on eip155:8453 via x402
# Install: pip install "x402[requests,evm]>=2.24,<3"
# The session reads the 402 (payment-required), signs and retries with payment-signature.
import os
from eth_account import Account
from x402 import x402ClientSync
from x402.http import decode_payment_response_header
from x402.http.clients.requests import x402_requests
from x402.mechanisms.evm.exact import register_exact_evm_client
from x402.mechanisms.evm.signers import EthAccountSigner

account = Account.from_key(os.environ["EVM_PRIVATE_KEY"])
client = x402ClientSync()
register_exact_evm_client(client, EthAccountSigner(account), networks="eip155:8453")
session = x402_requests(client)

payload = {
    "email": "[email protected]",
    "check_mx": False
}

res = session.post("https://grist.tools/v1/email-validate", json=payload)
print(res.status_code, res.json())
settle = res.headers.get("payment-response")
if settle:
    print(decode_payment_response_header(settle).transaction)

curl

# email-validate: $0.002 per call, paid in USD Coin on eip155:8453 via x402
# 1. Unpaid call: HTTP 402, the requirements in the payment-required header (base64 JSON) and in the body.
curl -i -X POST 'https://grist.tools/v1/email-validate' -H 'content-type: application/json' -d '{"email":"[email protected]","check_mx":false}'

# 2. Same call with the signed payment (an EIP-3009 authorization, EIP-712 signed: it cannot be
#    typed by hand). x-payment is accepted as the v1 alternative. HTTP 200 carries payment-response.
curl -i -X POST 'https://grist.tools/v1/email-validate' -H 'content-type: application/json' -H 'payment-signature: <base64 x402 payload>' -d '{"email":"[email protected]","check_mx":false}'

06Errors

Code	HTTP	For this service
invalid_input	400	The body does not match the schema; its fields are email, check_mx and check_disposable.
unreachable_target	424
upstream_timeout	424
internal	500

Input that is rejected before the tool runs (malformed JSON, schema mismatch, body over the size limit) is never charged.

When each code is raised, and what it means for payment: /docs/email-validate.

07Questions

How much does a email-validate call cost?: $0.002 per call, paid in USDC on Base via x402, with no account and no API key.
What does email-validate return?: A JSON object with 7 top-level fields: email, valid, syntax_valid, mx_found, mx_records, is_disposable and is_role_account. The example on this page is a real call.
What happens when a email-validate call fails?: The tool answers with a typed JSON error from the errors table. Payment is settled only after the tool has produced its result; a call that fails inside the tool is never settled. A 503 upstream_unavailable can follow a settled call; the x402 payments guide covers it, 429, 402 and an uncertain 500.