This document discusses setting up a Linux-based mail server. It begins with an introduction of the author and an explanation of why email is important. It then describes the basic email transfer process from Mail User Agent to Mail Transfer Agent to mailbox. The main components involved are outlined as the Mail Transfer Agent (MTA), Mail Delivery Agent (MDA), and Mail User Agent (MUA). Common protocols like SMTP, IMAP, and POP3 are also defined. Steps for installing and configuring Postfix as the MTA are provided, including adding domains and reloading the server.