OpenSMTPDThis is official OpenSMTPD Portable repository. Forks, pull requests and other contributions are welcome!

OpenSMTPD

OpenSMTPD is a free, open source implementation of the SMTP protocol that enables machines to send and receive emails across networks. It provides a secure, lightweight mail server solution that runs on multiple Unix-like operating systems including Linux, BSD variants, and macOS.

Key Features

• RFC 5321 Compliant : Fully implements the SMTP protocol with standard extensions for reliable email delivery
• Cross-Platform Support : Runs on Linux, FreeBSD, OpenBSD, NetBSD, DragonFlyBSD, and macOS
• Security-Focused : Designed with security as a core principle, supporting dual-user operation for privilege separation
• Easy Installation : Available through package managers for most distributions or installable from source

Use Cases

• Mail Server Deployment : Set up a complete SMTP mail server for organizations or personal use
• Email Infrastructure : Enable machines to exchange emails using standard SMTP protocol
• Legacy System Compatibility : Provide sendmail and postfix-compatible interfaces for existing systems

Who Is It For

OpenSMTPD is ideal for system administrators, developers, and organizations seeking a lightweight, secure, and standards-compliant SMTP server. It's suitable for anyone looking to establish email infrastructure on Unix-like systems without the complexity of larger mail server solutions.