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.):

json

{
  "mcpServers": {
    "email-send": {
      "url": "https://email-send.api.klymax402.com/mcp"
    }
  }
}

Quickstart -- HTTP (x402)

bash

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:

json

{"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)