Postfix
Postfix is a free and open-source mail transfer agent (MTA) software used for routing and delivering email on Unix-like operating systems. It is designed as a secure, fast, and easy-to-administer alternative to the older Sendmail MTA, with a modular architecture that separates different mail processing functions. Postfix handles tasks such as receiving, queuing, and forwarding emails between mail servers and clients.
Developers should learn Postfix when setting up or maintaining email servers for applications, websites, or organizational infrastructure, as it is widely used for reliable email delivery in production environments. It is particularly valuable for system administrators and DevOps engineers who need to configure secure mail services, implement spam filtering, or integrate with other tools like Dovecot for IMAP/POP3. Use cases include hosting email for web applications, managing transactional emails, and ensuring compliance with email security standards like SPF and DKIM.