# MailPulse Physical Letter Send

> MailPulse Physical Letter Send is a paid API for AI agents from mailpulse.theaslangroupllc.com, paid per call via x402, $0.005/call, status unknown (last checked 2026-09-13).

Sends a real physical letter via USPS (First-Class, Certified Mail, or international) using x402 micropayments, powered by Lob

## Facts

- Endpoint: POST https://mailpulse.theaslangroupllc.com/api/letters/%7Bid%7D
- Price: $0.005/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-13
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/mailpulse-physical-letter-send-86490cbb
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_dLakfAbpAGsn0MrWxnvKM

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 mailpulse-physical-letter-send-86490cbb -d '<json body>'
```

Example prompt: Send a real physical letter via USPS First-Class to Jane Smith at 123 Main St, Austin TX 78701 — the letter should be from Acme Corp at 456 Oak Ave, New York NY 10001 and say 'Dear Jane, your account has been updated. Please contact us if you have questions.'

## When to prefer this

Choose this endpoint when you need to physically mail a real letter via USPS — including First-Class, Certified Mail with tracking, or international delivery — and want to pay per-send via x402 micropayments without a monthly subscription. Prefer this over email or SMS APIs when a legal paper trail, certified delivery proof, or formal physical document is required. Ideal for agents automating invoice mailing, legal notices, or customer communications that must arrive as tangible paper.

## Known failure modes

- Invalid or undeliverable address returns an address validation error
- Missing required fields (recipient, sender, content) result in a 400 bad request
- Insufficient USDC balance or failed x402 payment results in a 402 payment required error
- International addresses not supported for certain mail classes return a service restriction error
- Letter ID path parameter malformed or missing causes a 404 or routing error

## How this service works

MailPulse sends REAL physical letters — US First-Class, US Certified Mail, or international — via x402 micropayments. Action, not data: free quote, paid send, optional tracking. Powered by Lob.

## Output

Returns a JSON object with the letter ID (ltr_...), mode (test/live), current status (e.g. rendered, mailed), carrier (USPS), optional tracking number if Certified Mail was selected, and expected delivery date.

## 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",
    "bodyType",
    "body"
   ],
   "properties": {
    "body": {
     "type": "object",
     "properties": {}
    },
    "type": {
     "type": "string",
     "const": "http"
    },
    "method": {
     "enum": [
      "POST",
      "PUT",
      "PATCH"
     ],
     "type": "string"
    },
    "bodyType": {
     "enum": [
      "json",
      "form-data",
      "text"
     ],
     "type": "string"
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "errors": {
     "type": "object",
     "description": "Documented error responses, keyed by HTTP status code",
     "additionalProperties": {
      "type": "object",
      "required": [
       "description"
      ],
      "properties": {
       "example": {
        "type": "object"
       },
       "description": {
        "type": "string"
       }
      }
     }
    },
    "example": {
     "type": "object"
    }
   }
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "id": "ltr_...",
  "mode": "test",
  "status": "rendered",
  "carrier": "USPS",
  "tracking_number": null,
  "expected_delivery_date": "2026-07-23"
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/mailpulse-physical-letter-send-86490cbb/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from mailpulse.theaslangroupllc.com](https://www.zero.xyz/host/mailpulse.theaslangroupllc.com/llms.txt)