A Bit about Email

The email system is composed of multiple components, including the mail user agent, submission agent, mail transfer agent, local delivery agent, and mail server, each with specific roles and configurations. The mail system was designed to handle limited internet connectivity and server maintenance, resulting in features like message retrying and exponential backoff. The submission agent and local delivery agent have become more complex with the rise of remote email access. Most communication happens over the Simple Internet Mail Access Protocol (SMTP).