# SMTP Domain Deliverability Validator

> SMTP Domain Deliverability Validator is a paid API for AI agents from defi-intel-agent-gateway.gg-neo15.workers.dev, paid per call via x402, $0.003/call, status unknown (last checked 2026-09-15).

Validates an email domain's deliverability by performing an SMTP handshake (without sending any email) and returning MX records, server greetings, and a deliverability verdict.

## Facts

- Endpoint: POST https://defi-intel-agent-gateway.gg-neo15.workers.dev/v1/net/smtp-ping
- Price: $0.003/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-15
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/smtp-domain-deliverability-validator-811c4951
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_ANaPFhrXOcBvx3ymzmfEo

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 smtp-domain-deliverability-validator-811c4951 -d '<json body>'
```

Example prompt: Can you check whether the domain 'acme-corp.com' can actually receive emails — without sending anything — and tell me the MX records and whether it's deliverable?

## When to prefer this

Use this endpoint when you need to verify whether an email domain is reachable and deliverable before sending real emails, enriching CRM records, or cleaning contact lists — especially when you want MX record details and an SMTP-level verdict without triggering any actual mail delivery. Prefer this over simple DNS lookups when you need SMTP-layer confirmation, and over paid email validation SaaS when you want pay-per-call pricing with no account setup.

## Known failure modes

- Domain has no MX records — returns empty MX list and non-deliverable verdict
- SMTP server times out or refuses connection — returns connection error and unresolvable verdict
- Domain does not exist in DNS — returns DNS lookup failure
- Rate limit hit for free daily samples — returns 402 payment required
- Malformed or missing domain input — returns validation error

## How this service works

Validate an email DOMAIN by performing an SMTP handshake WITHOUT sending. DO NOT use for bulk emailing. Returns MX records, greets, and a deliverability verdict. — $0.003 USDC/call on Base. Pay-per-call via x402 — no API key, no account. Free samples daily.

## Output

Returns a JSON object containing the domain's MX records, the SMTP server greeting string(s), and a deliverability verdict indicating whether the domain is reachable and can accept mail — without any email being sent.

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/smtp-domain-deliverability-validator-811c4951/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from defi-intel-agent-gateway.gg-neo15.workers.dev](https://www.zero.xyz/host/defi-intel-agent-gateway.gg-neo15.workers.dev/llms.txt)