sendmail

Sendmail is a widely-used command line tool for managing email transport on Unix-like operating systems. It was developed by Eric Allman in the 1980s and is known for its flexibility and extensive features.

1. Sendmail acts as a Mail Transfer Agent (MTA) and is responsible for routing and delivering outgoing email messages.
2. It is a powerful and robust tool that supports various email protocols like SMTP, POP, and IMAP.
3. Sendmail is highly configurable and can be customized to fit different mail server setups and requirements.
4. It allows users to send email from the command line, making it useful for scripting and automation purposes.
5. With its extensive error handling and delivery options, Sendmail can handle various scenarios like connection failures, DNS resolution issues, and temporary delivery failures.
6. It includes advanced features such as aliasing and forwarding, allowing users to redirect or filter incoming email messages based on specific criteria.
7. Sendmail supports multiple delivery modes, including submitting mail directly to the target server or delivering it to a local mailbox.
8. It offers various security features to protect against spam, spoofing, and unauthorized access, including robust authentication mechanisms and the ability to block specific domains or addresses.
9. Sendmail has a rich set of configuration files that define its behavior, allowing administrators to fine-tune its functionality to meet their specific needs.
10. Despite being one of the oldest MTA software, Sendmail continues to be actively maintained and updated to ensure compatibility with modern email protocols and requirements.