# DNS SRV Record Lookup for Mail Submission (_submission._tcp)

> DNS SRV Record Lookup for Mail Submission (_submission._tcp) is a paid API for AI agents from agentshelf.syntexa.ch, paid per call via x402, $0.009/call, status unknown (last checked 2026-10-02).

Resolves SRV records at _submission._tcp.{hostname} for a given registrable domain, returning mail submission server details.

## Facts

- Endpoint: POST https://agentshelf.syntexa.ch/v1/dns-srv-submission?utm_source=zero.xyz
- Price: $0.009/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-02
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/dns-srv-record-lookup-for-mail-submission-submission-tcp-315e534a
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_KcHeF_z55HgpRAzosQMMu

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 dns-srv-record-lookup-for-mail-submission-submission-tcp-315e534a -d '<json body>'
```

Example prompt: Can you look up the SRV records for mail submission for the domain example.com? I need to know which server and port handle email submission there.

## When to prefer this

Use this endpoint when an agent needs to programmatically discover the mail submission server and port for a domain via DNS SRV records, especially for email client auto-configuration, infrastructure auditing, or routing decisions. Prefer the free sandbox endpoint (POST /v1/sandbox/dns-srv-submission) when available to avoid the $0.009 USDC cost.

## Known failure modes

- Domain has no _submission._tcp SRV record in DNS — returns empty or NXDOMAIN result
- Invalid or malformed hostname input — returns validation error
- DNS resolution timeout or upstream failure — returns error response
- Non-registrable or non-existent domain provided — may return no records

## How this service works

Call when an agent needs SRV records at _submission._tcp.{hostname} for mail submission. The caller sends the registrable domain, not the underscored name. Exact $0.009 USDC. Prefer unpaid POST /v1/sandbox/dns-srv-submission first.

## Output

Returns SRV record data for _submission._tcp.{hostname}, including the mail submission server's target hostname, port, priority, and weight as found in DNS.

## 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/dns-srv-record-lookup-for-mail-submission-submission-tcp-315e534a/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)