# Email Deliverability Diagnostic

> Email Deliverability Diagnostic is a paid API for AI agents from agent402.tools, paid per call via x402, $0.009/call, status unknown (last checked 2026-09-14).

Diagnoses why a domain's email lands in spam by checking SPF posture, DMARC policy, DKIM key strength, MX targets, and returning a composite 0–100 deliverability score.

## Facts

- Endpoint: POST https://agent402.tools/api/skill/email-deliverability
- Price: $0.009/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-14
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/email-deliverability-diagnostic-6db7f33b
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_398EI0JSiu-wbxec5kKQ8

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-deliverability-diagnostic-6db7f33b -d '<json body>'
```

Example prompt: Can you diagnose why emails from acmecorp.com might be landing in spam — check the SPF, DMARC, DKIM, and MX setup and give me an overall deliverability score?

## When to prefer this

Use this endpoint when you need a comprehensive, one-call email deliverability audit covering all major authentication and routing signals (SPF, DMARC, DKIM, MX) plus a composite score — rather than calling individual DNS lookup tools separately. Ideal for agents diagnosing spam delivery issues or auditing email infrastructure for any domain.

## Known failure modes

- Invalid or non-existent domain returns an error or empty DNS results
- Domain with no DNS records returns null/missing fields for SPF, DMARC, DKIM
- Private or internal domains unreachable via public DNS may return no results
- Rate limiting or payment failure may block the call
- Partial results if some DNS records are missing but others are present

## How this service works

Bundled execution of the Email deliverability workflow - Diagnose why a domain's email lands in spam: SPF posture, DMARC policy, DKIM key strength, MX targets, and a composite 0–100 score. One x402 payment runs 6 underlying tools (spf-check, dmarc-check, dkim-lookup, email-deliverability, email-validate, dns-lookup); partial-success per step.

## Output

Returns a structured report covering SPF posture, DMARC policy details, DKIM key strength, MX record targets, and a composite 0–100 deliverability score — all from a single bundled execution of 6 underlying email diagnostics tools.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "domain": {
   "type": "string",
   "description": "Sending domain to diagnose (e.g. stripe.com)"
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "args": {
   "domain": "example.com"
  },
  "pack": "email-deliverability",
  "steps": [
   {
    "ok": true,
    "slug": "spf-check",
    "result": {}
   },
   {
    "ok": true,
    "slug": "dmarc-check",
    "result": {}
   },
   {
    "ok": true,
    "slug": "dkim-lookup",
    "result": {}
   },
   {
    "ok": true,
    "slug": "email-deliverability",
    "result": {}
   },
   {
    "ok": true,
    "slug": "email-validate",
    "result": {}
   },
   {
    "ok": true,
    "slug": "dns-lookup",
    "result": {}
   }
  ],
  "summary": "6/6 steps succeeded"
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/email-deliverability-diagnostic-6db7f33b/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from agent402.tools](https://www.zero.xyz/host/agent402.tools/llms.txt)