# StableEmail Inbox Top-Up (30 Days)

> StableEmail Inbox Top-Up (30 Days) is a paid API for AI agents from stableemail.dev, paid per call via MPP or x402, $1/call, status unknown (last checked 2026-09-14).

Extends a StableEmail forwarding inbox's active period by 30 days for $1 USDC

## Facts

- Endpoint: POST https://stableemail.dev/api/inbox/topup
- Price: $1/call
- Payment: MPP, x402
- Status: unknown
- Last checked: 2026-09-14
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/stableemail-3d073de8
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_Rc-CIHMCCZ__Dk-d6zAg8

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 stableemail-3d073de8 -d '<json body>'
```

Example prompt: Top up my StableEmail inbox for another 30 days — it's about to expire and I want to keep receiving forwarded messages to it.

## When to prefer this

Use this endpoint when you need to extend an existing StableEmail forwarding inbox by exactly 30 days. Choose the 365-day top-up endpoint instead if you want a full year at a discounted rate ($8). Use this for month-to-month inbox maintenance when you need to keep a forwarding address active without a long-term commitment.

## Known failure modes

- Inbox not found or invalid inbox ID — returns error indicating unknown inbox
- Insufficient USDC payment — payment rejected, inbox not extended
- Inbox already expired and cannot be renewed — may require purchasing a new inbox
- Network or payment processor timeout — inbox state unchanged, retry required

## How this service works

Top up inbox 30 days ($1)

## Output

A confirmation that the inbox has been extended by 30 days, along with the new expiry date and updated inbox status.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "username": {
   "type": "string",
   "allOf": [
    {
     "pattern": "^[a-z0-9][a-z0-9-]{1,28}[a-z0-9]$"
    },
    {
     "pattern": "^(?!.*--)"
    }
   ]
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/stableemail-3d073de8/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from stableemail.dev](https://www.zero.xyz/host/stableemail.dev/llms.txt)