Postfix

Postfix is an open-source mail server software that routes and delivers electronic mail. It's known for its speed, security, and ease of configuration.

Key Features

• High performance mail delivery
• Robust security features
• Flexible configuration options
• Supports SMTP and several other protocols
• Extensive documentation and community support

Pros

• Free and open-source
• Highly customizable for specific needs
• Scalable for small to large environments
• Strong community and regular updates

Cons

• Steeper learning curve for new users
• Limited GUI management options
• Some advanced features require manual configuration
• Potential performance issues with very high mail volumes