Email Deliverability Verification (SMTP)

Checks whether an email address really exists by asking its mail server (SMTP RCPT TO probe; no email is sent), on top of syntax, MX, disposable and role checks. Returns status deliverable, undeliverable (mailbox does not exist), catch_all (domain accepts any address), risky (disposable or mailbox full) or unknown (greylisting, server refused the check), plus the raw SMTP reply. Use it before sending outreach, to clean lead lists or to block fake sign-ups. Results are cached 6 hours. Params: email (required).

Call it

import { wrapFetchWithPayment, x402Client } from "@x402/fetch";
import { registerExactEvmScheme } from "@x402/evm/exact/client";
import { privateKeyToAccount } from "viem/accounts";

const client = new x402Client();
registerExactEvmScheme(client, { signer: privateKeyToAccount(process.env.EVM_PRIVATE_KEY) });
const payFetch = wrapFetchWithPayment(fetch, client);

const res = await payFetch("https://agentsvc.io/api/v1/proxy/email-verify", {
  method: "POST",
  headers: { "Content-Type": "application/json" },
  body: JSON.stringify({"email":"support@github.com"}),
});
const { data, payment } = await res.json();  // payment.transaction = on-chain receipt

Input

Output

Example response (data)

{
  "email": "support@github.com",
  "status": "deliverable",
  "deliverable": true,
  "reason": "mailbox_exists",
  "is_catch_all": null,
  "is_disposable": false,
  "is_role_address": true,
  "is_free_provider": false,
  "format_valid": true,
  "domain": "github.com",
  "mx_records": [
    "github-com.mail.protection.outlook.com"
  ],
  "smtp": {
    "mx": "github-com.mail.protection.outlook.com",
    "code": 250,
    "message": "2.1.5 Recipient OK",
    "catch_all_code": 452
  },
  "note": "SMTP mailbox probe (RCPT TO). No email was sent.",
  "checked_at": "2026-10-06T16:05:40.287Z"
}