x402_send_email

Send transactional emails with HTML/plain text, CC/BCC recipients, and file attachments via Resend. Paid mode costs $0.01 USDC per email with daily limits, or use free test mode for fixture data.

Instructions

Send a transactional email via Resend. Price: $0.01 USDC per email (paid mode) | Free test: returns fixture data.

Supports plain text or HTML body, CC/BCC recipients, and file attachments (base64-encoded, max 25MB per file). Per-wallet daily limit: 10 emails. Per-domain daily limit: 5 emails (applies to all recipients including CC/BCC). Without X402_PRIVATE_KEY, only the free test endpoint is available.

Returns: message_id from Resend.

Input Schema

TableJSON Schema

Name	Required	Description
`to`	Yes	Recipient email address
`subject`	Yes	Email subject (max 998 chars)
`body`	Yes	Email body — HTML or plain text (max 100 KB)
`reply_to`	No	Optional reply-to address
`cc`	No	CC recipients — list of email addresses
`bcc`	No	BCC recipients — list of email addresses
`attachments`	No	File attachments (base64-encoded, max 25MB pre-encoding per file)

Implementation Reference

src/index.ts:513-545 (handler)

The handler for the x402_send_email tool, which handles both paid (via Resend) and free (test) email sending logic.

async (params) => {
  const base = APIS.email.baseUrl;

  try {
    const usePaid = !!PRIVATE_KEY;

    if (usePaid) {
      const payload: Record<string, unknown> = {
        to: params.to,
        subject: params.subject,
        body: params.body,
      };
      if (params.reply_to) payload.reply_to = params.reply_to;
      if (params.cc) payload.cc = params.cc;
      if (params.bcc) payload.bcc = params.bcc;
      if (params.attachments) payload.attachments = params.attachments;

      const data = await apiPost(base, "/send", payload, true);
      return textResult({
        mode: "paid",
        cost: "$0.01",
        ...data,
      });
    } else {
      const data = await apiGet(base, "/send/test");
      return textResult({
        mode: "free_test",
        note: "Free test — no email actually sent. Set X402_PRIVATE_KEY for real email delivery.",
        ...data,
      });
    }
  } catch (err: any) {
    return errorResult(err.message);

src/index.ts:485-512 (schema)

The Zod schema validation for the input parameters of the x402_send_email tool.

{
  to: z.string().email().describe("Recipient email address"),
  subject: z
    .string()
    .min(1)
    .max(998)
    .describe("Email subject (max 998 chars)"),
  body: z
    .string()
    .min(1)
    .max(102400)
    .describe("Email body — HTML or plain text (max 100 KB)"),
  reply_to: z
    .string()
    .email()
    .optional()
    .describe("Optional reply-to address"),
  cc: z.array(z.string().email()).optional()
      .describe("CC recipients — list of email addresses"),
  bcc: z.array(z.string().email()).optional()
      .describe("BCC recipients — list of email addresses"),
  attachments: z.array(z.object({
      filename: z.string().describe("Filename including extension (e.g. 'report.pdf')"),
      content: z.string().describe("Base64-encoded file content (max 25MB decoded)"),
      content_type: z.string().optional()
          .describe("MIME type — auto-derived from filename if omitted"),
  })).optional().describe("File attachments (base64-encoded, max 25MB pre-encoding per file)"),
},

src/index.ts:476-476 (registration)
Registration of the x402_send_email tool in the server instance.
```
"x402_send_email",
```

x402 MCP Server

x402_send_email

Instructions

Input Schema

Implementation Reference

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