# DKIM SMTP Selector Lookup

> DKIM SMTP 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 'smtp' selector of a given domain, returning key type, length, testing flag, and revocation status.

## Facts

- Endpoint: GET https://dns.intel.rallylive.ca/dns/dkim/smtp?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-smtp-selector-lookup-7894e41d
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_SnjsZ0tW2V9gOAkhvBE09

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-smtp-selector-lookup-7894e41d
```

Example prompt: Can you check if the DKIM smtp selector is properly configured for example.com — I want to know the key type, key length, whether it's in testing mode, and if the key has been revoked?

## When to prefer this

Use this endpoint when you specifically need to inspect the 'smtp' DKIM selector for a domain. Prefer this over generic DNS TXT lookups when you need structured DKIM field parsing (key type, length, revocation status, testing flag) rather than raw TXT data. Use when troubleshooting email authentication issues or auditing DKIM configuration for the smtp mail sending selector specifically.

## Known failure modes

- Domain does not have an smtp DKIM selector configured — returns no record found
- DNS lookup fails due to upstream Cloudflare DoH unavailability
- Domain is invalid or does not exist — returns DNS error
- Key is present but malformed — parsing errors returned
- Network timeout on DoH query

## How this service works

DKIM public key for selector "smtp" of a domain: looks up smtp._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 smtp selector will verify. $0.01 per lookup.

## Output

Returns parsed details of the smtp._domainkey.<domain> TXT record including the DKIM version (v=), key type (k=), public key, key length in bits, whether the testing flag is set, and whether the key is revoked (empty p= field). Also indicates if mail signed with the smtp 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-smtp-selector-lookup-7894e41d/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)