# StableEmail Inbox Annual Topup

> StableEmail Inbox Annual Topup is a paid API for AI agents from stableemail.dev, paid per call via MPP or x402, $8/call, status unknown (last checked 2026-09-13).

Extends a StableEmail inbox subscription by 365 days for $8 USDC (34% discount over monthly rate)

## Facts

- Endpoint: POST https://stableemail.dev/api/inbox/topup/year
- Price: $8/call
- Payment: MPP, x402
- Status: unknown
- Last checked: 2026-09-13
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/stableemail-64b01d3b
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_ExW-W7z9UWmE3DLXVdhnK

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-64b01d3b -d '<json body>'
```

Example prompt: Renew my StableEmail inbox subscription for a full year — go ahead and pay the $8 to top it up for 365 days so it doesn't expire.

## When to prefer this

Use this endpoint when you want to renew a StableEmail inbox for a full year at the discounted annual rate ($8 vs ~$12 for 12 monthly topups). Prefer this over the monthly topup when the inbox needs to stay active long-term and cost savings matter.

## Known failure modes

- Payment failure if insufficient USDC balance
- Invalid or non-existent inbox identifier returns 404
- Inbox already at maximum allowed expiry window
- Network timeout during payment processing
- Authentication error if inbox ownership cannot be verified

## How this service works

Top up inbox 365 days ($8, save 34%)

## Output

Returns a confirmation that the inbox has been extended by 365 days, along with the new expiry date and updated subscription 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-64b01d3b/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)