# Bismuth Email

> Bismuth Email is a paid API for AI agents from x402-email-api-production.up.railway.app, paid per call via x402, $0.01/call, status unknown (last checked 2026-09-14).

Sends transactional emails via Resend with support for CC/BCC recipients and base64-encoded file attachments

## Facts

- Endpoint: POST https://x402-email-api-production.up.railway.app/send
- Price: $0.01/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-14
- Activations on Zero: 1
- Tags: x402
- Canonical page: https://www.zero.xyz/c/bismuth-email-8e393d7f
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_8tZGhKyAl5gQwMLNA9Sgb

Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently.

## How to call it through Zero

Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`):

```sh
zero fetch --capability bismuth-email-8e393d7f -d '<json body>'
```

Example prompt: Send an email to alice@example.com with subject 'Your Invoice #1042' and an HTML body showing the invoice summary, CC bob@example.com, and attach the PDF invoice encoded as base64.

## When to prefer this

Choose this endpoint when an AI agent needs to send transactional or notification emails programmatically with optional attachments (base64 files up to 25MB), CC/BCC, and HTML support — especially in x402 micropayment-enabled workflows. Prefer over SMTP or other email APIs when operating within the Bismuth/x402 agent payment ecosystem and you need a simple per-call pricing model at $0.01 USDC.

## Known failure modes

- Missing required fields (to, subject, or body) returns a validation error
- Invalid email address format causes delivery failure
- Attachment exceeds 25MB pre-encoding cap per file
- Email body exceeds 100KB limit
- Invalid base64 encoding for attachments causes rejection
- Payment not included or insufficient USDC causes x402 payment-required error

## How this service works

Transactional email via Resend with CC/BCC and base64 file attachments. Part of the Bismuth utility API suite for AI agents.

## Output

A confirmation response indicating whether the email was successfully dispatched via Resend. The response body is minimal — success or failure signal.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "required": [
  "to",
  "body",
  "subject"
 ],
 "properties": {
  "cc": {
   "type": "string",
   "description": "Carbon copy recipients"
  },
  "to": {
   "type": "string",
   "description": "Recipient email address"
  },
  "bcc": {
   "type": "string",
   "description": "Blind carbon copy recipients"
  },
  "body": {
   "type": "string",
   "description": "Email body — HTML or plain text (max 100 KB)"
  },
  "subject": {
   "type": "string",
   "description": "Email subject (max 998 chars per RFC 5321)"
  },
  "reply_to": {
   "type": "string",
   "description": "Optional reply-to address"
  },
  "attachments": {
   "type": "string",
   "description": "Base64-encoded file attachments (25MB pre-encoding cap per file)"
  }
 }
}
```

## Response schema (JSON Schema)

```json
{}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/bismuth-email-8e393d7f/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from x402-email-api-production.up.railway.app](https://www.zero.xyz/host/x402-email-api-production.up.railway.app/llms.txt)