Dev Mail Box

A lightweight local SMTP server with a clean Flask-based web UI for viewing and sending test emails — perfect for development environments.

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🚀 Features

• Local SMTP Server – Captures all outgoing mail on 127.0.0.1:1025
• Web UI – Browse messages, view raw source, send new messages
• No External SMTP – No username/password required
• Cross-Platform – Runs on Windows, macOS, and Linux
• Packagable – Build to .exe with PyInstaller for easy sharing on Windows

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📦 Installation

Option 1 – Using uv (Recommended)

uv sync

Installs all dependencies from pyproject.toml or requirements.txt.

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Option 2 – Using pip

pip install -r requirements.txt

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▶️ Running the App

python main.py

You’ll see output like:

📨 SMTP server running on 127.0.0.1:1025
🌐 Web UI available at http://127.0.0.1:5000

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🌍 Usage

1. Point your app’s SMTP settings to:

   • Host: 127.0.0.1
   • Port: 1025
   • Username / Password: (Leave blank)

2. Access the Web UI: Open http://127.0.0.1:5000 in your browser.

3. View Messages: Browse captured messages, read full content, or view raw email source.

4. Send a Test Email: Use the Send page in the UI to send a new message to the SMTP server.

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🛠 Building to EXE (Optional)

Using PyInstaller:

pyinstaller --onefile main.py

The compiled executable will be inside the dist/ folder.

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📥 Download Release

Get the latest Windows executable here: https://github.com/jztchl/devmailbox/releases

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📄 Requirements

Minimal dependencies:

Flask>=3.0.0
aiosmtpd>=1.4.5

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📜 License

MIT License — use freely for development purposes.