# ProbeKit DKIM Selector Discovery

> ProbeKit DKIM Selector Discovery is a paid API for AI agents from api.probekit.dev, paid per call via x402, $0.02/call, status unknown (last checked 2026-10-30).

Tries 27 common DKIM selectors for a domain and validates every key found, including type, size, revocation status, and testing flag

## Facts

- Endpoint: GET https://api.probekit.dev/v1/mail/dkim-discover?utm_source=zero.xyz
- Price: $0.02/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-30
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/probekit-dkim-selector-discovery-c49283c7
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_Voai5EfD6Kw8souv7Ar31

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 probekit-dkim-selector-discovery-c49283c7
```

Example prompt: Can you discover what DKIM selectors are active for acme.com? I don't know which selector they're using — probe the common ones like Google, Microsoft 365, SendGrid, and Mailchimp and tell me what keys you find and whether they're valid.

## When to prefer this

Choose this endpoint when you need to discover DKIM keys for a domain but don't know the selector in advance. It covers 27 well-known selectors from major providers (Google, Microsoft 365, Mailchimp, SendGrid, Mailgun, Zoho, Proton, Fastmail, Mailjet, Amazon SES) and validates every key found. Use the sibling single-selector endpoint instead if you already know the exact selector name.

## Known failure modes

- Domain does not exist or has no DNS — all 27 selectors return not found
- DNS timeout or resolver error — partial or empty results
- Domain uses a non-standard selector not in the 27 probed — key not discovered
- Malformed domain input — validation error returned
- Rate limiting or payment failure — 402 or 429 error

## How this service works

Try 27 common DKIM selectors (Google, Microsoft 365, Mailchimp, SendGrid, Mailgun, Zoho, Proton, Fastmail, Mailjet, Amazon SES and generic names) for a domain and validate every key found: type, size, revocation and testing flag. Use when an agent needs a domain's DKIM keys but does not know the selector. Finding none is a hint, not proof that DKIM is missing.

## Output

A list of probed selectors with results for each: which selectors returned a DKIM record, the public key found, key type (e.g. RSA), key size in bits, whether the key is revoked, and whether the testing flag is set. Selectors with no DNS record are indicated as not found. Finding no keys is noted as a hint rather than definitive proof DKIM is absent.

## 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",
      "HEAD",
      "DELETE"
     ],
     "type": "string"
    },
    "queryParams": {
     "type": "object",
     "title": "DomainInput",
     "required": [
      "domain"
     ],
     "properties": {
      "domain": {
       "type": "string",
       "title": "Domain",
       "examples": [
        "example.com"
       ],
       "maxLength": 1024,
       "minLength": 1
      }
     },
     "additionalProperties": false
    }
   },
   "additionalProperties": false
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/probekit-dkim-selector-discovery-c49283c7/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from api.probekit.dev](https://www.zero.xyz/host/api.probekit.dev/llms.txt)