Postfix

Postfix is a mail transfer agent that routes and delivers e-mail.

Configuration

Postfix stores its configuration files in the /etc/postfix/ directory. The following is a list of the more commonly used files:

access: Used for access control, this file specifies which hosts are allowed to connect to Postfix.
aliases: A configurable list required by the mail protocol.
main.cf: The global Postfix configuration file. The majority of configuration options are specified in this file.
master.cf: Specifies how Postfix interacts with various processes to accomplish mail delivery.
transport: Maps email addresses to relay hosts.