MPPtempoquality 0.88

Extend a StableEmail forwarding inbox by 30 days for $1 USDC via micropayment.

Price
$1.00 / call
Protocol
mpp
Verified
no
Endpoint
https://stableemail.dev/api/inbox/topup

What it does

This endpoint extends an existing StableEmail forwarding inbox (username@stableemail.dev) by 30 days for $1 USDC. It is part of the StableEmail platform, which provides pay-per-send email delivery, forwarding inboxes, and custom subdomains — all without API keys or accounts. Payments are handled via the x402/MPP micropayment protocol, settling in USDC on Base (eip155:8453), Solana, or Tempo. Anyone can top up any inbox; no wallet ownership proof (SIWX) is required.

The request body takes a single required field: the username of the inbox to extend. On success, the response includes the new expiration date, total days remaining, and confirmation that 30 days were added. Bulk discount alternatives exist at /api/inbox/topup/quarter (90 days for $2.50, ~17% savings) and /api/inbox/topup/year (365 days for $8, ~34% savings).

StableEmail inboxes can forward to a real email address, retain messages for programmatic API access, or both. Inbox owners can also send from their inbox address ($0.005/email), check status, update forwarding settings, and cancel with a pro-rata USDC refund. The recommended agent integration path is via agentcash-skills (MCP server or CLI), which handles payment negotiation automatically.

Capabilities

email-inbox-topupforwarding-inboxmicropayment-emailx402-paymentmpp-paymentusdc-settlementbase-chainsolana-chaintempo-chainduration-extensionno-auth-required

Use cases

  • —Automatically renew a forwarding inbox for an AI agent that needs a persistent email address
  • —Top up a teammate's or friend's inbox without needing their wallet credentials
  • —Programmatically maintain inbox availability in a scheduled cron job
  • —Keep a disposable email address alive for ongoing project communications

Fit

Best for

  • —AI agents needing persistent email addresses without account management
  • —Developers who want programmatic inbox lifecycle management via micropayments
  • —Users who want anonymous or wallet-based email forwarding with no signup

Not for

  • —High-volume transactional email (use dedicated ESP like SendGrid or SES directly)
  • —Users who need traditional email hosting with IMAP/SMTP client access

Quick start

# Top up an inbox for 30 days ($1 USDC)
curl -X POST https://stableemail.dev/api/inbox/topup \
  -H 'Content-Type: application/json' \
  -d '{"username": "alice"}'
# Returns 402 → pay with any x402/MPP client → resend with payment header

Example

Request

{
  "username": "alice"
}

Response

{
  "inbox": "alice",
  "success": true,
  "daysAdded": 30,
  "expiresAt": "2025-08-15T00:00:00.000Z",
  "daysRemaining": 45
}

Endpoint

URLhttps://stableemail.dev/api/inbox/topup
Transporthttp
Protocolmpp
CurrencypathUSD

Quality

0.88/ 1.00

Full OpenAPI 3.1 schema with detailed x-guidance documentation, clear pricing ($1 USDC), and complete request/response structure. The endpoint returned 405 on HEAD/GET probes, which is expected since it's a POST-only endpoint — the OpenAPI spec confirms it is live. No dedicated docs page exists (404), but the llms.txt guidance is comprehensive.

Warnings

  • —Probe returned 405 on HEAD/GET because this is a POST-only endpoint; not an indication of downtime
  • —No dedicated /docs page exists (returns 404); documentation is embedded in OpenAPI x-guidance and the landing page

Citations

Provenance

Indexed frommpp_dev
Enriched2026-04-19 16:06:04Z · anthropic/claude-opus-4.6 · v2
First seen2026-04-18
Last seen2026-04-22

Agent access

JSONhttps://clawmart.sh/api/listings/Gw3WeA