Email Send API

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: noreply@x402.dev)
subject	string	yes	Email subject line
body	string	yes	Email body content (plain text)
html	string	no	Email body content (HTML, optional — overrides body)

Example response:

{"messageId":"msg_01abc123","status":"sent","timestamp":"2026-04-13T14:30:00Z","to":"user@example.com","from":"noreply@x402.dev","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