# DKIM MX Selector Lookup

> DKIM MX Selector Lookup is a paid API for AI agents from dns.intel.rallylive.ca, paid per call via x402, $0.01/call, status unknown (last checked 2026-10-20).

Looks up and parses the DKIM public key for the 'mx' selector of a given domain, returning key type, length, testing flag, and revocation status.

## Facts

- Endpoint: GET https://dns.intel.rallylive.ca/dns/dkim/mx?utm_source=zero.xyz
- Price: $0.01/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-20
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/dkim-mx-selector-lookup-a9f3a1d2
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_qsgmV09QH8oeShjQkIVOJ

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 dkim-mx-selector-lookup-a9f3a1d2
```

Example prompt: Can you check if the DKIM mx selector is properly configured for example.com — specifically whether the public key is valid, what key type it uses, and whether it's been revoked?

## When to prefer this

Use this endpoint when you specifically need to verify the 'mx' DKIM selector for a domain — as opposed to other common selectors like 'mailgun', 'google', or 'default'. It is ideal for diagnosing email deliverability issues, auditing email security posture, or confirming that DKIM signing via the mx selector is active and not revoked before initiating mail flows.

## Known failure modes

- Domain has no mx._domainkey TXT record — returns not found or empty result
- DNS query fails due to Cloudflare DoH outage or connectivity issue
- Domain does not exist or is mistyped — DNS NXDOMAIN response
- Key is revoked (empty p=) — endpoint reports revocation rather than failing
- Malformed TXT record that cannot be parsed — partial result or parse error
- Payment not provided or insufficient — 402 Payment Required response

## How this service works

DKIM public key for selector "mx" of a domain: looks up mx._domainkey.<domain> (TXT, Cloudflare DoH) and parses v=, k=, key type, public-key length, testing flag and whether the key is revoked (empty p=). Confirms that mail signed with the mx selector will verify. $0.01 per lookup.

## Output

Returns parsed DKIM record fields for the mx selector including: version (v=DKIM1), key type (k=rsa or ed25519), public key length in bits, whether the testing flag (t=y) is set, and whether the key is revoked (empty p= value). Also confirms whether mail signed with the mx selector will successfully verify.

## 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",
     "properties": {}
    }
   },
   "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/dkim-mx-selector-lookup-a9f3a1d2/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from dns.intel.rallylive.ca](https://www.zero.xyz/host/dns.intel.rallylive.ca/llms.txt)