# Agent Email Check – Batch Email Validation

> Agent Email Check – Batch Email Validation is a paid API for AI agents from mail.halowerk.com, paid per call via x402, $0.001/call, status unknown (last checked 2026-09-14).

Validates up to 100 email addresses per call using DNS and list-based checks, with optional SMTP probing, billed per address.

## Facts

- Endpoint: POST https://mail.halowerk.com/email/batch
- Price: $0.001/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-14
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/agent-email-check-batch-email-validation-622b89e7
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_Ifz0Nu3HXVKY3XnGs9iLk

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 agent-email-check-batch-email-validation-622b89e7 -d '<json body>'
```

Example prompt: Can you check these 50 email addresses for validity — I want to know which ones are deliverable before I send the campaign, and please run SMTP probes on them too.

## When to prefer this

Use this endpoint when you need to validate multiple email addresses in one round-trip and want to minimize cost through batching. It is ideal for list hygiene before email campaigns, CRM cleanups, or filtering sign-ups. Prefer this over single-address validators when you have 2–100 addresses to check. The optional SMTP probe is valuable when DNS-only results are insufficient, but be aware it is throttled and not retried.

## Known failure modes

- Submitting more than 100 emails returns a validation error
- Submitting an empty array returns a validation error
- SMTP checks are heavily throttled and only attempted once per address — results may be absent or inconclusive
- Some domains block SMTP probes, leaving verdicts as 'unknown' even with smtp_check enabled
- Malformed email strings may be flagged as invalid without detailed reasoning

## How this service works

Check up to 100 email addresses in one paid call, billed per address.

## Output

For each submitted email address, the endpoint returns a verdict on validity and deliverability based on DNS and blocklist checks. If SMTP probing is enabled, a best-effort probe result is included — though without SMTP the verdict for routable addresses remains 'unknown'. Results cover up to 100 addresses per call, billed at 0.0006 USDC per address with a 0.001 USDC minimum.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "emails": {
   "type": "array",
   "items": {
    "type": "string"
   },
   "maxItems": 100,
   "minItems": 1,
   "description": "Between 1 and 100 addresses. Billed at 0.0006 USDC per address with a 0.001 USDC minimum charge."
  },
  "smtp_check": {
   "type": "boolean",
   "default": false,
   "description": "Ask for an optional SMTP probe. Off by default, heavily throttled, one attempt per target and never retried. Without it the verdict of a routable address stays \"unknown\"."
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/agent-email-check-batch-email-validation-622b89e7/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from mail.halowerk.com](https://www.zero.xyz/host/mail.halowerk.com/llms.txt)