# Email System Simple batch email sender (Node + Express). Prerequisites - Node.js 18+ Quick start 1. Copy `.env.example` to `.env` and fill in your secrets. ```powershell npm install node backend/server.js ``` Server will verify SMTP credentials on startup. Use `x-api-key` header for authenticated requests. Frontend Open `frontend/index.html` (served statically or via a simple static server). The frontend uses `fetch` to call the API at `http://localhost:4000` by default. Security notes - Do NOT embed real API keys in frontend JS. For production, implement a server-side session/token flow or a proxy endpoint. - Add DKIM/SPF records for deliverability. # emails