# DKIM TXT Record Lookup – mail._domainkey selector

> DKIM TXT Record Lookup – mail._domainkey selector is a paid API for AI agents from agentshelf.syntexa.ch, paid per call via x402, $0.005/call, status unknown (last checked 2026-10-01).

Fetches the DNS TXT record at mail._domainkey.{hostname} to retrieve the DKIM public key for the 'mail' selector

## Facts

- Endpoint: POST https://agentshelf.syntexa.ch/v1/dns-txt-dkim-mail?utm_source=zero.xyz
- Price: $0.005/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-01
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/dkim-txt-record-lookup-mail-domainkey-selector-b8dae735
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_yvPDRTFJ9iYQ-CiAwr0vs

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-txt-record-lookup-mail-domainkey-selector-b8dae735 -d '<json body>'
```

Example prompt: Can you look up the DKIM TXT record at mail._domainkey for example.com and tell me what public key is configured there?

## When to prefer this

Use this endpoint when you specifically need to check the 'mail' DKIM selector (mail._domainkey) for a domain. Choose sibling endpoints for other common selectors (default, dkim, k1, ses, smtp, etc.). Use the sandbox/unpaid POST /v1/sandbox/dns-txt-dkim-mail first if you want to test without spending $0.005 USDC. Prefer this over general DNS TXT lookup endpoints when you want a selector-specific DKIM check without SPF or other TXT records mixed in.

## Known failure modes

- Hostname does not have a mail._domainkey TXT record (NXDOMAIN or empty response)
- Invalid or malformed hostname input exceeding 253 characters
- DNS resolution timeout or upstream DNS failure
- Payment not processed or insufficient USDC balance causing request rejection

## How this service works

Call when an agent needs TXT at mail._domainkey.{hostname}. A different selector is a different DNS name. Exact $0.005 USDC. Prefer unpaid POST /v1/sandbox/dns-txt-dkim-mail first.

## Output

Returns the DNS TXT record content published at mail._domainkey.{hostname}, typically a DKIM public key entry in the format v=DKIM1; k=rsa; p=<base64-encoded-public-key>. If no record exists the response will indicate absence or an empty result.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "hostname": {
   "type": "string",
   "examples": [
    "example.com"
   ],
   "maxLength": 253,
   "minLength": 1,
   "description": "Public DNS hostname such as example.com. Not a URL, not an IP literal, and not a private name."
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/dkim-txt-record-lookup-mail-domainkey-selector-b8dae735/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from agentshelf.syntexa.ch](https://www.zero.xyz/host/agentshelf.syntexa.ch/llms.txt)