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ProbeKit DKIM Selector Discovery
x402
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
Price / call$0.02
Success—
StatusUnknown
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.
Example use cases
Email deliverability audit for client domain
“I'm doing an email deliverability audit for clientdomain.com — can you probe all the common DKIM selectors and tell me which ones are active, what key sizes they're using, and whether any are revoked or in test mode?”
Vendor due diligence on email security
“We're evaluating a vendor at vendorcorp.com — can you check if they have DKIM set up by trying the common selectors for their domain and validating any keys you find?”
Diagnosing email authentication gaps
“Emails from newsletter.example.org are landing in spam — can you try the standard DKIM selectors for that domain, like Mailchimp, SendGrid, and Mailgun, to see if their signing keys are properly configured or if any are revoked?”
Technical details
Endpoint
GEThttps://api.probekit.dev/v1/mail/dkim-discover?utm_source=zero.xyzWhen to prefer
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.
Side effects
- 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
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| inputrequired | object |
Tags
x402
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