Postfix is a Mail Transfer Agent(MTA) for routing and delivering electronic mail(email). Dovecot is a secure IMAP and POP3 Mail Delivery Agent(MDA). These two open-source applications work well with Roundcube, an email client primarily famous for its clever use of Ajax technology. In this guide, you'll install Postfix, Dovecot, and Roundcube on Ubuntu 20.04. This guide uses the domain **example.com** and the server name **mail.example.com**. Before you begin, make sure you have the following: * ......