Temporary Email API for Developers — Complete Guide 2026

GoneBox offers a REST API and MCP Server for automated temporary email management. Developers can create disposable inboxes, poll for incoming messages, and delete inboxes programmatically — all without a browser. This makes it possible to automate email verification flows in CI/CD pipelines, integration tests, and AI agent workflows where a human can't be in the loop.

The temporary email API market is growing fast. AgentMail raised $6M in 2025 specifically for AI-agent email infrastructure. MailSink, Mail.tm, and Guerrilla Mail offer limited APIs. GoneBox combines a clean REST API with an MCP Server — the only service that lets AI agents like Claude and Cursor manage email natively through the Model Context Protocol.

Why Developers Need a Temporary Email API

Automated Testing

Every application with user registration needs to test the signup flow end-to-end. That means creating a real email address, triggering the verification email, extracting the verification link, and clicking it. Without an API, this requires manual intervention or fragile hacks with shared inboxes. A temp email API makes it a 3-line function call.

CI/CD Pipelines

Continuous integration pipelines run hundreds of tests per day. If even 5% of those tests involve email verification, you need a reliable, high-throughput email API that creates fresh inboxes on demand and doesn't rate-limit you into the ground. GoneBox's Startup plan handles 10,000 requests/day at 300 requests/minute.

AI Agent Workflows

AI agents (Claude, GPT, Cursor, Windsurf) increasingly perform multi-step tasks that require email verification. An agent signing up for a service on your behalf needs to create an inbox, read the verification email, extract the code, and proceed. The MCP Server makes this native — no custom HTTP plumbing required.

API Overview

GoneBox's API is REST-based, uses JSON, and requires an API key for authenticated endpoints.

Base URL

https://api.gonebox.email/v1

Authentication

Authorization: Bearer YOUR_API_KEY

Core Endpoints

Method	Endpoint	Description
POST	/inboxes	Create a new temporary inbox
GET	/inboxes/:id	Get inbox details (address, TTL, message count)
GET	/inboxes/:id/messages	List messages in the inbox
GET	/inboxes/:id/messages/:msgId	Get a specific message (headers, body, attachments)
DELETE	/inboxes/:id	Delete inbox immediately (before TTL)

Create an Inbox — curl

curl -X POST https://api.gonebox.email/v1/inboxes \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{"domain": "gonebox.email", "ttl": 3600}'

Response:

{
  "id": "inbox_abc123",
  "address": "[email protected]",
  "ttl": 3600,
  "expiresAt": "2026-05-19T15:30:00Z",
  "messagesUrl": "/v1/inboxes/inbox_abc123/messages"
}

MCP Server for AI Agents

The Model Context Protocol (MCP) is an open standard that lets AI agents interact with external tools natively. GoneBox's MCP Server exposes temporary email operations as MCP tools, so any MCP-compatible client can manage inboxes without writing HTTP code.

Available MCP Tools

• create_inbox — Create a temporary inbox with optional domain and TTL
• list_messages — List messages in an inbox
• read_message — Read a specific message's content
• delete_inbox — Delete an inbox immediately

Claude Desktop Example

Add to your Claude Desktop MCP config:

{
  "mcpServers": {
    "gonebox": {
      "command": "npx",
      "args": ["-y", "@gonebox/mcp-server"],
      "env": {
        "GONEBOX_API_KEY": "YOUR_API_KEY"
      }
    }
  }
}

Then ask Claude: "Create a temporary email, sign up for X, and read the verification code." Claude will use the MCP tools automatically.

Code Examples

JavaScript / Node.js

const API_KEY = process.env.GONEBOX_API_KEY;
const BASE = 'https://api.gonebox.email/v1';

// Create inbox
const inbox = await fetch(`${BASE}/inboxes`, {
  method: 'POST',
  headers: {
    'Authorization': `Bearer ${API_KEY}`,
    'Content-Type': 'application/json',
  },
  body: JSON.stringify({ domain: 'gonebox.email' }),
}).then(r => r.json());

console.log(`Inbox: ${inbox.address}`);

// Wait for messages (poll every 2s)
let messages = [];
while (messages.length === 0) {
  await new Promise(r => setTimeout(r, 2000));
  messages = await fetch(`${BASE}/inboxes/${inbox.id}/messages`, {
    headers: { 'Authorization': `Bearer ${API_KEY}` },
  }).then(r => r.json());
}

console.log(`Received: ${messages[0].subject}`);

Python

import requests, time, os

API_KEY = os.environ["GONEBOX_API_KEY"]
BASE = "https://api.gonebox.email/v1"
headers = {"Authorization": f"Bearer {API_KEY}"}

# Create inbox
inbox = requests.post(f"{BASE}/inboxes",
    headers={**headers, "Content-Type": "application/json"},
    json={"domain": "gonebox.email"}
).json()

print(f"Inbox: {inbox['address']}")

# Poll for messages
messages = []
while not messages:
    time.sleep(2)
    messages = requests.get(
        f"{BASE}/inboxes/{inbox['id']}/messages",
        headers=headers
    ).json()

print(f"Received: {messages[0]['subject']}")

Rate Limits and Pricing

Plan	Price	Daily Requests	Rate Limit	Max TTL
Free	$0	100	10/min	1 hour
Dev	$15/mo	1,000	60/min	24 hours
Startup	$49/mo	10,000	300/min	24 hours
Enterprise	$199/mo	100,000	1,000/min	24 hours

Comparison with Alternatives

Service	REST API	MCP Server	Free Tier	Pricing
GoneBox	Yes	Yes	100 req/day	From $15/mo
AgentMail	Yes	No	Limited	Enterprise pricing
Mail.tm	Yes	No	Unlimited	Free only
MailSink	Yes	No	No	From $19/mo
Guerrilla Mail	Unofficial	No	Yes	Free only

Getting Started in 30 Seconds

1. Go to gonebox.email and create a free account
2. Copy your API key from the dashboard
3. Run the curl command above to create your first inbox
4. For AI agents, install the MCP Server: npx @gonebox/mcp-server