Simple SMTP Client

A simple and to the point SMTP test client

Built with .NET 10 - Modern, fast, and secure!

Features

1. Download the release under the "release" tab.
2. Supports Basic Authentication to SMTP server.
3. Supports Anonymous connection to SMTP Server.
4. Supports TLS/SSL encryption with modern MailKit library:
   • TLS 1.0, TLS 1.1, TLS 1.2, and TLS 1.3 (automatically negotiated)
   • Auto/System Default mode for automatic protocol negotiation
   • Secure by default with TLS 1.2+ recommended
   • Works with SMTP servers in STARTTLS mode only. Does not support connecting to SMTP/SSL, SMTP over SSL, or SMTPS server on default port 465.
5. Runs on Windows (requires .NET 10 Runtime or later).
6. Modern async/await implementation for better performance and responsiveness.
7. Input validation for all required fields with helpful error messages.
8. Configurable connection timeout (5-300 seconds) with ability to cancel ongoing operations.
9. Save/Load settings - Your SMTP server configuration is automatically saved and restored between sessions.
10. Logging feature - All connection attempts, successes, and failures are logged to daily log files:
    • View logs directly in the application
    • Open log folder in File Explorer
    • Automatic cleanup of logs older than 30 days
    • Toggle logging on/off as needed

Settings Storage

Settings and logs are stored in:

• Windows: %LOCALAPPDATA%\SimpleSmtpClient\
  • settings.json - Application settings
  • Logs\ - Daily log files

Note: Passwords are never saved to disk for security reasons.