# Email Preflight Validation API

> Email Preflight Validation API is a paid API for AI agents from x402-canary.nicolas-x402-16f380a7.workers.dev, paid per call via x402, $0.02/call, status unknown (last checked 2026-09-15).

Validates an email address for syntax correctness and MX record existence before sending

## Facts

- Endpoint: POST https://x402-canary.nicolas-x402-16f380a7.workers.dev/v1/email/preflight
- Price: $0.02/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-15
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/email-preflight-validation-api-3abfe74d
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_aMHPmsDdcdaPt53C78c_K

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 email-preflight-validation-api-3abfe74d -d '<json body>'
```

Example prompt: Can you do a preflight check on john.doe@example.com to see if the syntax is valid and the domain actually accepts email?

## When to prefer this

Choose this endpoint when you need a lightweight, fast preflight check combining both syntax validation and MX record lookup in a single call before sending email or accepting user input. Prefer this over full email verification services when you need only basic deliverability signals (syntax + MX) without SMTP handshake or inbox verification, and when cost-per-call economics via x402/USDC micropayments fit your use case.

## Known failure modes

- Invalid or missing email field returns validation error
- Non-existent or unreachable domain may cause MX lookup timeout
- Malformed JSON input returns parse error
- Payment not provided or insufficient USDC balance returns 402 Payment Required
- DNS resolution failures may cause has_mx to return false even for valid domains

## How this service works

Free need-to-tool routing plus pay-per-call npm docs and TypeScript API signatures, npm breaking-change diffs, JavaScript-rendered browser snapshots and deterministic coding-agent checks via AgentCash/x402.

## Output

Returns a JSON object with a data field containing has_mx (boolean indicating whether the domain has valid MX DNS records) and syntax_valid (boolean indicating whether the email address is syntactically well-formed), plus a meta field with engine identifier 'email-preflight'.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "email": {
   "type": "string"
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "data": {
   "has_mx": true,
   "syntax_valid": true
  },
  "meta": {
   "engine": "email-preflight"
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/email-preflight-validation-api-3abfe74d/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from x402-canary.nicolas-x402-16f380a7.workers.dev](https://www.zero.xyz/host/x402-canary.nicolas-x402-16f380a7.workers.dev/llms.txt)