Email address check
What can be told about an email address without sending anything to it: whether the syntax is valid, whether the domain can receive mail at all, and whether it is a known disposable provider, a free consumer provider, or a role address like support@ that no single person reads. For filtering a signup list or deciding whether a contact address is worth writing to.
POST https://api.bottrunk.com/s/email-check
Call it
# once, on the machine your agent runs on npx bottrunk-mcp wallet # prints the address; send it 0.3 ALGO, then USDC claude mcp add bottrunk -- npx -y bottrunk-mcp # then ask your agent for it — the tool is `bottrunk_email_check`
# Ask. You get a 402 with the payment requirements.
curl https://api.bottrunk.com/s/email-check \
-H "Content-Type: application/json" \
-d '{"email":"support@stripe.com"}'
# Pay and retry. Any x402 client does this for you.
curl https://api.bottrunk.com/s/email-check \
-H "PAYMENT-SIGNATURE: <signed USDC transfer>" \
-H "Content-Type: application/json" \
-d '{"email":"support@stripe.com"}'
# pip install "x402-avm[avm,requests]==2.0.2"
import base64, os
from algosdk import encoding, mnemonic
from x402 import x402ClientSync
from x402.http import x402HTTPClientSync
from x402.http.clients.requests import x402_requests
from x402.mechanisms.avm import ALGORAND_MAINNET_CAIP2
from x402.mechanisms.avm.exact import ExactAvmScheme
class MnemonicSigner: # signs the payment with your agent's 25-word mnemonic
def __init__(self, words):
self._sk = mnemonic.to_private_key(words)
self.address = encoding.encode_address(base64.b64decode(self._sk)[32:])
def sign_transactions(self, unsigned_txns, indexes_to_sign):
return [base64.b64decode(encoding.msgpack_encode(
encoding.msgpack_decode(base64.b64encode(t).decode()).sign(self._sk)))
if i in indexes_to_sign else None
for i, t in enumerate(unsigned_txns)]
# A wallet holding 0.3 ALGO, opted in to USDC, funded with the USDC it may spend.
signer = MnemonicSigner(os.environ["ALGORAND_MNEMONIC"])
client = x402ClientSync().register(ALGORAND_MAINNET_CAIP2,
ExactAvmScheme(signer, algod_url="https://mainnet-api.algonode.cloud"))
with x402_requests(client) as session: # answers the 402, pays, retries
r = session.post("https://api.bottrunk.com/s/email-check", json={"email": "support@stripe.com"})
print(r.json())
receipt = x402HTTPClientSync(client).get_payment_settle_response(r.headers.get)
print(receipt.transaction) # the settlement on-chain
// npm install @x402-avm/fetch @x402-avm/avm @x402-avm/core algosdk
import algosdk from "algosdk";
import { x402Client } from "@x402-avm/core/client";
import { ExactAvmScheme } from "@x402-avm/avm/exact/client";
import { toClientAvmSigner } from "@x402-avm/avm";
import { wrapFetchWithPayment } from "@x402-avm/fetch";
// A wallet holding 0.3 ALGO, opted in to USDC, funded with the USDC it may spend.
const { sk } = algosdk.mnemonicToSecretKey(process.env.ALGORAND_MNEMONIC!);
const signer = toClientAvmSigner(Buffer.from(sk).toString("base64"));
const client = new x402Client().register("algorand:wGHE2Pwdvd7S12BL5FaOP20EGYesN73ktiC1qzkkit8=",
new ExactAvmScheme(signer, { algodUrl: "https://mainnet-api.algonode.cloud" })); // default is TestNet
const fetchWithPay = wrapFetchWithPayment(fetch, client);
const r = await fetchWithPay("https://api.bottrunk.com/s/email-check", {
method: "POST",
headers: { "Content-Type": "application/json" },
body: JSON.stringify({"email":"support@stripe.com"}),
});
console.log(await r.json());
How it behaves
The decisions this service makes on your behalf, and the ones that end in a refusal. A 4xx is never settled, so a refusal costs you nothing.
| What this is not | Not a mailbox check. Proving an address exists needs an SMTP probe, which is unreliable and gets the prober blocked, so we do not do it. No mail is ever sent. |
| Deliverable domain | True when the domain publishes MX records, or an A record that mail can fall back to. It says the domain can receive mail, not that this mailbox does. |
| Bad syntax | Answered 200 with valid_syntax: false and no DNS lookup — a malformed address is a fact about the input, not a failure. |
| Disposable and free lists | Known-provider lists, not exhaustive. A false on either means we did not recognise it. |
| If DNS is unreachable | The call fails and is never settled, so it costs you nothing. |
| Method | POST only. A GET on the same path returns this page. |
Input
| string | Address to check. |
Output
| valid_syntax | boolean | Whether the address parses as an email address. |
| domain | string | Domain part, lowercased. |
| mx | array | Mail exchangers, lowest preference first. |
| deliverable_domain | boolean | Whether the domain can receive mail at all. |
| disposable | boolean | Known disposable-provider domain. |
| free_provider | boolean | Known free consumer provider. |
| role_account | boolean | Role address like support@ or billing@. |