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The start command runs the production version of the preview app that was built using the build command.

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Usage

email start

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Prerequisites

Before running email start, you must first build the preview app: 
email build
This creates a .react-email directory with the production-ready preview app.

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How It Works

When you run email start, the CLI:
  1. Checks that the .react-email directory exists
  2. Runs next start on the built application
  3. Starts a production server (default port: 3000)
  4. Serves your email templates with optimal performance

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Example Workflow

Complete workflow for production preview: 
# Build the preview app
email build

# Start the production server
email start
Terminal output: 
✔ Ready on http://localhost:3000

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Default Port

By default, the preview app starts on port 3000. The port is configured during the build process. To use a different port, you can set it in Next.js configuration before building, or use Next.js CLI directly: 
cd .react-email
npx next start -p 8080

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Production vs Development

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Development Server (email dev)

  • Hot reloading enabled
  • Slower initial load
  • Real-time file watching
  • Development mode
  • Best for active development

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Production Server (email start)

  • No hot reloading
  • Optimized performance
  • Pre-rendered static pages
  • Production mode
  • Best for demos and deployment

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Use Cases

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Local Preview

Preview the production build locally before deploying: 
email build
email start

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Sharing with Team

Share a production-quality preview with your team:
  1. Build the app: email build
  2. Start the server: email start
  3. Share the URL: http://localhost:3000
For remote access, use a tunneling service: 
email start &
npx localtunnel --port 3000

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QA Testing

Use the production build for quality assurance: 
email build --dir ./src/emails
email start
This ensures you’re testing the exact output that will be deployed.

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Stopping the Server

To stop the server, press Ctrl+C in the terminal. The CLI handles graceful shutdown:
  • Ongoing requests complete
  • Server processes are cleaned up
  • Port is released

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Deployment

For actual deployment, you have several options:

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Deploy to Vercel

cd .react-email
vercel

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Deploy to Netlify

cd .react-email
netlify deploy --prod

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Self-Hosted

Run the production server on your own infrastructure: 
# Using PM2
cd .react-email
pm2 start "npm start" --name react-email-preview

# Using systemd
[Unit]
Description=React Email Preview
After=network.target

[Service]
Type=simple
User=www-data
WorkingDirectory=/path/to/.react-email
ExecStart=/usr/bin/npm start
Restart=on-failure

[Install]
WantedBy=multi-user.target

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Docker

Create a Docker image: 
FROM node:18-alpine
WORKDIR /app
COPY .react-email .
WORKDIR /app/.react-email
EXPOSE 3000
CMD ["npm", "start"]
Build and run: 
docker build -t react-email-preview .
docker run -p 3000:3000 react-email-preview

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Environment Variables

The production server uses environment variables configured during build:
  • REACT_EMAIL_INTERNAL_EMAILS_DIR_ABSOLUTE_PATH - Absolute path to email templates
  • REACT_EMAIL_INTERNAL_EMAILS_DIR_RELATIVE_PATH - Relative path to email templates
  • REACT_EMAIL_INTERNAL_PREVIEW_SERVER_LOCATION - Location of preview server files
  • REACT_EMAIL_INTERNAL_USER_PROJECT_LOCATION - User’s project root
These are automatically set during email build and don’t need manual configuration.

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Troubleshooting

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Directory Not Found

If you see “Could not find .react-email”: 
# Solution: Build first
email build
email start

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Port Already in Use

If port 3000 is occupied: 
# Option 1: Use Next.js directly with custom port
cd .react-email
npx next start -p 8080

# Option 2: Kill the process using port 3000
lsof -ti:3000 | xargs kill -9
email start

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Stale Build

If changes aren’t reflected:
  1. Stop the server (Ctrl+C)
  2. Rebuild: email build
  3. Restart: email start

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Performance Issues

For better performance:
  1. Ensure you’re using the latest Node.js LTS version
  2. Check that the build completed successfully
  3. Monitor server resources (CPU, memory)

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Next Steps

Build Command

Learn about building the preview app

Export Templates

Export templates as static HTML files

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