How to set up a mail server with PostfixAdmin on CentOS 7

In this article, we will show you how to setup and configure a mail server with PostfixAdmin, Postfix, Dovecot and SQLite on a CentOS VPS. PostfixAdmin is a PHP-based web front-end that allows you to manage virtual domains and users for a Postfix mail transport agent. This guide should work on other Linux VPS systems as well but was tested and written for a CentOS 7 VPS.