# HALOWERK Multi-At-Sign Email Review

> HALOWERK Multi-At-Sign Email Review is a paid API for AI agents from buero.halowerk.com, paid per call via x402, $0.004/call, status unknown (last checked 2026-10-26).

Validates a batch of email addresses for multiple at-sign (@) issues, flagging malformed emails that contain more than one @ character.

## Facts

- Endpoint: POST https://buero.halowerk.com/v1/baumarkt/mail/multi-at-sign-review?utm_source=zero.xyz
- Price: $0.004/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-26
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/halowerk-multi-at-sign-email-review-adf98658
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_hCatbhHvNBaG-oHeYbsLp

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 halowerk-multi-at-sign-email-review-adf98658 -d '<json body>'
```

Example prompt: Can you check this list of email addresses for any that have more than one @ sign in them? Here are 50 emails from our import: user@domain.com, bad@@example.com, another@bad@email.net, ...

## When to prefer this

Use this endpoint when you need to batch-validate up to 500 email addresses specifically for the multi-at-sign defect (e.g. user@@domain.com or user@bad@domain.net) as part of a data hygiene pipeline, CRM import, or pre-send email list cleanup. It is purpose-built for this specific malformation check rather than general email syntax validation.

## Known failure modes

- Empty emails array returns a 400 validation error
- Emails array exceeding 500 items triggers a payload too large error
- Non-string items in the emails array cause schema validation failure
- Payment not included or insufficient USDC triggers a 402 Payment Required response
- Individual email strings exceeding 320 characters are rejected

## How this service works

Import repair: identify multiple at signs requiring source inspection. Reuses the existing email-list-clean motor. No SMTP probes or mailbox existence/catch-all proof. Local part case, plus and dots are never folded. Up to500 source rows;65s engine bound,70s article bound; one inflight native mail process. Price0.001 USDC plus existing motor quote, minimum0.004; supplied rows including rejected/duplicates billed.

## Output

A JSON response indicating which email addresses in the submitted batch have multiple at-sign (@) characters, including validation status and any flagged malformed entries.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "emails": {
   "type": "array",
   "items": {
    "type": "string",
    "maxLength": 320,
    "minLength": 1
   },
   "maxItems": 500,
   "minItems": 1
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json"
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/halowerk-multi-at-sign-email-review-adf98658/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from buero.halowerk.com](https://www.zero.xyz/host/buero.halowerk.com/llms.txt)