# Mailcheck by Hergertsynthora

> Mailcheck by Hergertsynthora is a paid API for AI agents from mailcheck.hergertsynthora.com, paid per call via x402, $0.05/call, status down (last checked 2026-09-15).

Validates an email address via RFC syntax check, live MX lookup, disposable-domain detection, role-account flagging, and deliverability scoring without sending any mail

## Facts

- Endpoint: POST https://mailcheck.hergertsynthora.com/service
- Price: $0.05/call
- Payment: x402
- Status: down
- Last checked: 2026-09-15
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/mailcheck-by-hergertsynthora-6fc3713c
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_Cd9DMzez3gluYXnsGr_Pj

Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently.

## How to call it through Zero

Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`):

```sh
zero fetch --capability mailcheck-by-hergertsynthora-6fc3713c -d '<json body>'
```

Example prompt: Can you check whether 'j.doe+test@gmail.com' is a real, deliverable email — flag if it's disposable, a role address, or from a free provider, and give me the normalized gmail form?

## When to prefer this

Choose this endpoint when you need comprehensive, multi-signal email validation without sending any mail — especially when you need disposable-domain detection (daily-refreshed blocklist), role-account flagging, and cryptographically signed results. Prefer over simple regex or syntax-only validators when deliverability and fraud prevention matter. Ideal for sign-up flows, lead qualification, and pre-send list scrubbing.

## Known failure modes

- Missing or malformed input: no email field provided returns a 400-level error
- Invalid JSON body: returns parse error
- Email with completely invalid syntax may return syntax-fail with no MX lookup attempted
- MX lookup timeout or DNS failure may return a degraded deliverability hint
- Payment not included or insufficient: x402 payment required error before validation is run
- Blocklist may have up to 24-hour lag for newly created disposable domains

## How this service works

Email address validation without sending mail: RFC syntax check, live MX lookup, disposable-domain detection (daily-refreshed blocklist), role-account and free-provider flags, gmail normalization and a deliverability hint. Deterministic, Ed25519-signed. $0.001 via x402 USDC on Base.

## Output

Returns structured validation results including: RFC syntax pass/fail, live MX lookup result, boolean flag for disposable/throwaway domain (from a daily-refreshed blocklist), boolean flag for role accounts (e.g. info@, support@), boolean flag for free email providers, normalized gmail address (dots removed, alias stripped), and an overall deliverability hint — all deterministically computed and signed with Ed25519 for tamper evidence.

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "ok": true,
  "niche": "mailcheck",
  "result": {
   "email": "user@example.com",
   "status": "deliverable",
   "mx_found": true,
   "confidence": 90,
   "deliverable_hint": true
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/mailcheck-by-hergertsynthora-6fc3713c/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from mailcheck.hergertsynthora.com](https://www.zero.xyz/host/mailcheck.hergertsynthora.com/llms.txt)