# HALOWERK buerowerk SMTP Octet-Compatibility Email Validator

> HALOWERK buerowerk SMTP Octet-Compatibility Email Validator is a paid API for AI agents from buero.halowerk.com, paid per call via x402, $0.004/call, status unknown (last checked 2026-10-22).

Validates a list of email addresses for SMTP octet-compatibility, checking conformance with mail server constraints.

## Facts

- Endpoint: POST https://buero.halowerk.com/v1/baumarkt/mail/smtp-octet-compatibility?utm_source=zero.xyz
- Price: $0.004/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-22
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/halowerk-buerowerk-smtp-octet-compatibility-email-validator-5ca43c98
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_Ddf7KbqmazC4ZRC0IP6v2

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-buerowerk-smtp-octet-compatibility-email-validator-5ca43c98 -d '<json body>'
```

Example prompt: Can you check these email addresses for SMTP octet compatibility before I send my campaign: user@example.com, test.name+tag@domain.co, and weirdchar@münchen.de?

## When to prefer this

Choose this endpoint when you need to validate email addresses specifically for SMTP octet-level compatibility — particularly useful for international or unusual addresses before bulk sending, or when pre-screening user-submitted emails for mail server conformance. Prefer this over generic format validators when SMTP delivery compliance (not just RFC syntax) is the concern.

## Known failure modes

- Empty email array returns validation error
- Email strings exceeding 320 characters are rejected
- Array exceeding 500 items is rejected
- Malformed JSON body returns 400 error
- Payment not provided or insufficient USDC results in 402 response
- Invalid email format may cause per-item failure in response

## How this service works

HALOWERK buerowerk — bezahlte Endpunkte nach x402. Preise in USDC auf Base Mainnet.

## Output

A JSON response indicating the SMTP octet-compatibility status of each submitted email address, likely including per-address results or a summary of which addresses pass or fail SMTP octet constraints.

## 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-buerowerk-smtp-octet-compatibility-email-validator-5ca43c98/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)