This long post contains a recipe for building a reasonably secure Ubuntu 16.04 mail server in Amazon Web Services, using Postfix, Dovecot, and MySQL, with anti-spam packages in the form of amavisd-new, Clam AntiVirus, SpamAssassin, and Postgrey. Local users [are virtual][1] rather than being system users. Administration of users and domains is achieved through the Postfix Admin web interface. Webmail is provided by Roundcube.
This is an updated version of earlier [Ubuntu 12.04][2] and [Ubuntu 14.04][3] mailserver recipes. A number of people graciously helped to fix bugs and make improvements in the original, so should you find a blocking issue here please do let me know.
Introduction