EmptyInbox

Disposable email inbox API for AI agents and developers. Create temporary email addresses, receive messages, and read content — via REST API or MCP server.

Live at emptyinbox.me

MCP Server (Claude / Claude Code / Cursor / any MCP agent)

· Official MCP Registry: io.github.cnohall/emptyinbox · source and tool reference

Zero config. No API key: the server registers an account on its first tool call.

Terminal

claude mcp add emptyinbox -- npx -y emptyinbox-mcp

config.json

{
  "mcpServers": {
    "emptyinbox": {
      "command": "npx",
      "args": ["-y", "emptyinbox-mcp"]
    }
  }
}

Free inboxes to start. More are bought with Bitcoin from inside the agent session: buy_quota returns a payment page with a QR code for the user, and credits land within seconds of the payment being broadcast.

REST API

Base URL: https://emptyinbox.me/api Auth: Authorization: Bearer <api_key> OpenAPI spec: https://emptyinbox.me/openapi.yaml

bash

# Create an inbox
curl -X POST -H "Authorization: Bearer YOUR_KEY" https://emptyinbox.me/api/inbox

# List messages — filter to one inbox, only what arrived since the last poll
curl -H "Authorization: Bearer YOUR_KEY" \
  "https://emptyinbox.me/api/messages?inbox=ADDRESS&since=1711234000&include_body=false"

# Read a message
curl -H "Authorization: Bearer YOUR_KEY" https://emptyinbox.me/api/message/MSG_ID

# ...or as flat text, ready to drop into a prompt
curl -H "Authorization: Bearer YOUR_KEY" "https://emptyinbox.me/api/message/MSG_ID?format=text"

Every message comes back parsed, so nothing has to pick through the HTML:

config.json

{
  "subject": "Confirm your email address",
  "from_name": "Example App",
  "from_email": "noreply@example.com",
  "received_at": "2024-03-23T21:36:07Z",
  "type": "verification",
  "code": "482910",
  "action_url": "https://example.com/verify?token=abc123",
  "links": [{ "url": "https://example.com/verify?token=abc123", "text": "Verify your email" }],
  "preview": "Your verification code is 482910. It expires in 10 minutes.",
  "text": "Your verification code is 482910. It expires in 10 minutes."
}

text is the body flattened to plain text (from the HTML part when there is no text part), code is the best one-time code found, action_url the single link worth opening. ?format=raw still returns the untouched MIME parts.

Typical agent workflow

POST /api/inbox → get a disposable address
Use that address in an external signup or verification flow
GET /api/messages?inbox=<address>&since=<last timestamp> → poll until the verification email appears
Read code or action_url straight off the message — the API extracts both

Local Development

Backend (Flask, port 5000)

powershell

cd api
pipenv install
pipenv run create_db   # first run only — creates SQLite DB
pipenv run dev         # starts python tempmail_api.py with CORS + /api prefix

api/.env for local dev:

env

DOMAIN=localhost:8000
SECRET=any_random_string
FLASK_ENV=development
BLOCKONOMICS_API_KEY=<key>
USDT_RECEIVING_ADDRESS=<address>
MATCH_CALLBACK=ngrok

Frontend (static, port 8000)

powershell

cd static
python -m http.server 8000

Open http://localhost:8000. The JS auto-detects localhost and hits http://localhost:5000 for the API (static/utils/constants.js).

Self-hosting

Requirements

Ubuntu server
Python 3 + pipenv
Nginx
Postfix

Setup

1. Clone and configure

bash

git clone https://github.com/blockonomics/emptyinbox-me
cd emptyinbox-me/api
cp .env.example .env   # fill in your values

.env variables:

Code

DOMAIN=yourdomain.com
SECRET=your_postfix_webhook_secret
FLASK_ENV=production
BLOCKONOMICS_API_KEY=your_blockonomics_api_key
USDT_RECEIVING_ADDRESS=your_usdt_address
MATCH_CALLBACK=https://yourdomain.com/api/payments/callback

2. Database

bash

pipenv install
pipenv run create_db

3. Gunicorn

bash

pipenv run start

4. Nginx

bash

sudo cp nginx/emptyinbox_nginx.conf /etc/nginx/sites-available/emptyinbox_nginx.conf
sudo nginx -t && sudo systemctl reload nginx

5. Postfix

bash

sudo apt install postfix   # select "No configuration"
sudo cp /usr/share/postfix/main.cf.debian /etc/postfix/main.cf
sudo postfix/setup_postfix.sh YOUR_HOSTNAME YOUR_DOMAIN YOUR_SECRET

Pricing

Free: 5 inboxes per account
Paid: 1 USDT per 10 additional inboxes (via Blockonomics — no credit card, no KYC)