# Email Syntax Checker (RFC 5322, No DNS)

> Email Syntax Checker (RFC 5322, No DNS) is a paid API for AI agents from intel.rallylive.ca, paid per call via x402, $0.01/call, status unknown (last checked 2026-09-14).

Validates email address syntax against RFC 5322 rules — checking local part, domain shape, dots, invalid characters, missing TLD, and length limits — without performing any DNS lookup.

## Facts

- Endpoint: GET https://intel.rallylive.ca/email/syntax
- Price: $0.01/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-14
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/email-syntax-checker-rfc-5322-no-dns-e94b64a3
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_a11MRewR91IOiK4IeXopP

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-syntax-checker-rfc-5322-no-dns-e94b64a3
```

Example prompt: Can you check whether 'john..doe@example' is a valid email address format — just syntax, no DNS lookup needed?

## When to prefer this

Choose this endpoint when you need instant, sub-millisecond email format validation with no network dependency on DNS — ideal for real-time form validation, pre-filtering contact lists before DNS/SMTP checks, or agent pipelines where speed and offline-safe operation matter. Prefer it over MX-check or SMTP-verify endpoints when you only need structural correctness and cannot afford DNS latency or want to avoid external lookups.

## Known failure modes

- Missing email address parameter returns an error
- Malformed query string may result in a 400 bad request
- Payment not included or insufficient USDC results in a 402 Payment Required response
- Edge-case RFC ambiguities (e.g. quoted local parts) may not be fully handled

## How this service works

Fast email syntax check (no DNS): validates local part and domain shape per RFC 5322 practical rules, flags leading/trailing/double dots, invalid characters, missing TLD and length limits. Sub-millisecond input validation for forms and agents. $0.01 per address.

## Output

Returns a syntactic validity verdict for the submitted email address along with specific flags for any rule violations found, such as leading/trailing/double dots, invalid characters in the local part or domain, missing TLD, or violations of length limits — all evaluated purely against RFC 5322 practical rules with no DNS resolution.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "$schema": "https://json-schema.org/draft/2020-12/schema",
 "required": [
  "input"
 ],
 "properties": {
  "input": {
   "type": "object",
   "required": [
    "type",
    "method"
   ],
   "properties": {
    "type": {
     "type": "string",
     "const": "http"
    },
    "method": {
     "enum": [
      "GET"
     ],
     "type": "string"
    },
    "queryParams": {
     "type": "object",
     "properties": {}
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "type": "object"
    }
   }
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/email-syntax-checker-rfc-5322-no-dns-e94b64a3/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from intel.rallylive.ca](https://www.zero.xyz/host/intel.rallylive.ca/llms.txt)