Email Send API
Send emails programmatically via Resend -- text or HTML body, delivery status, message ID. Transactional email. Pay-per-call via x402 (USDC on Base L2) -- no API key, no signup, no rate-limit wall.
Part of the klymax402 marketplace -- 100 x402 micropayment APIs for AI agents, one wallet, USDC on Base.
Quickstart -- MCP
Add to your MCP client config (Claude Desktop, Cursor, ElizaOS, etc.):
{
"mcpServers": {
"email-send": {
"url": "https://email-send.api.klymax402.com/mcp"
}
}
}
Quickstart -- HTTP (x402)
curl -X POST "https://email-send.api.klymax402.com/api/send" \
-H "Content-Type: application/json" \
-d '{"to":"...","subject":"...","body":"..."}'
# -> 402 Payment Required, with an x402 payment challenge in the response body
Any x402-aware client (@x402/fetch, x402-agent-tools, ATXP) handles the 402 -> sign -> retry cycle automatically.
Tools
| Tool | Method | Path | Price | Description |
|---|---|---|---|---|
email_send_message | POST | /api/send | $0.008 | Send an email message |
email_send_message
Use this when you need to send an email to one or more recipients. Returns delivery confirmation in JSON.
Parameters
| Name | Type | Required | Description |
|---|---|---|---|
to | string | yes | Recipient email address |
from | string | no | Sender email address (default: [email protected]) |
subject | string | yes | Email subject line |
body | string | yes | Email body content (plain text) |
html | string | no | Email body content (HTML, optional β overrides body) |
Example response:
{"messageId":"msg_01abc123","status":"sent","timestamp":"2026-04-13T14:30:00Z","to":"[email protected]","from":"[email protected]","subject":"Your Report"}
When to use: sending transactional emails, notifications, alerts, password resets, order confirmations, and automated reports.
Not for: email validation (use email_verify_address), finding email addresses (use email_find_by_name), person data enrichment (use person_enrich_from_email).
Example agent prompts
- "Send an email to one or more recipients"
Payment
- Protocol: x402 -- HTTP-native pay-per-call, no signup, no API key
- Network: Base L2 (
eip155:8453) - Asset: USDC
- Facilitator: Coinbase CDP (primary), PayAI (fallback)
- Also reachable via ATXP (OAuth-wrapped x402, RFC 9728 protected-resource metadata)
Part of klymax402
100 x402 micropayment APIs for AI agents -- one wallet, USDC on Base, zero signup.
- Catalog: https://klymax402.com/llms.txt
- Full API reference: https://klymax402.com/llms-full.txt
- Live stats: https://klymax402.com/stats
License
MIT