# SiteCheck Web Intel MTA-STS Validator

> SiteCheck Web Intel MTA-STS Validator is a paid API for AI agents from api.webintel-api.workers.dev, paid per call via x402, $0.002/call, status unknown (last checked 2026-10-24).

Validates a mail domain's MTA-STS configuration by checking the _mta-sts TXT DNS record and the HTTPS policy file, reporting their presence, mode, MX patterns, and max_age.

## Facts

- Endpoint: GET https://api.webintel-api.workers.dev/api/security/mta-sts-validator?utm_source=zero.xyz
- Price: $0.002/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-24
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/sitecheck-web-intel-mta-sts-validator-2cd22fd3
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_fJXwb1_TR0xGDVI_Yb43L

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 sitecheck-web-intel-mta-sts-validator-2cd22fd3
```

Example prompt: Can you check the MTA-STS configuration for example.com — I want to know if the _mta-sts TXT record is present, what policy mode is set (enforce, testing, or none), and whether the HTTPS policy file is valid?

## When to prefer this

Use this endpoint when you need a quick, automated check of a mail domain's MTA-STS posture without standing up your own DNS resolver or HTTP client logic. It is ideal for email security audits, onboarding checks, compliance monitoring, and troubleshooting MTA-STS deployment issues. It does not test the actual mail servers, so pair it with SMTP-level checks if full delivery path validation is needed.

## Known failure modes

- Domain does not exist or has no DNS records — returns absence flags
- _mta-sts TXT record missing — returns record not found
- HTTPS policy file unreachable or returns non-200 — reports policy fetch failure
- Policy file present but malformed or missing required fields — reports invalid policy
- Network timeout fetching the policy file — may return error or partial result
- Domain parameter missing from query — likely returns 400 or validation error

## How this service works

Checks MTA-STS for a mail domain: the _mta-sts TXT record (v=STSv1 and id) and the HTTPS policy file (mode enforce, testing or none, the MX patterns and max_age). Reports whether the record and the policy are both present and whether the policy's version is valid. Does not test the mail servers themselves.

## Output

Returns whether the _mta-sts TXT DNS record exists with v=STSv1 and an id, whether the HTTPS policy file at /.well-known/mta-sts.txt is reachable and syntactically valid, the policy mode (enforce, testing, or none), the list of MX host patterns allowed, the max_age value, and an overall summary of whether both the record and policy are present and valid.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "$schema": "https://json-schema.org/draft/2020-12/schema",
 "required": [
  "input"
 ],
 "properties": {
  "input": {
   "type": "object",
   "required": [
    "type",
    "method"
   ],
   "properties": {
    "type": {
     "type": "string",
     "const": "http"
    },
    "method": {
     "enum": [
      "GET"
     ],
     "type": "string"
    },
    "queryParams": {
     "type": "object",
     "required": [
      "domain"
     ],
     "properties": {
      "domain": {
       "type": "string",
       "description": "Mail domain such as gmail.com (required)"
      }
     }
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "type": "object"
    }
   }
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/sitecheck-web-intel-mta-sts-validator-2cd22fd3/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from api.webintel-api.workers.dev](https://www.zero.xyz/host/api.webintel-api.workers.dev/llms.txt)