Linux Babe published a tutorial about creating virtual mailboxes with PostfixAdmin on CentOS/RHEL.
PostfixAdmin – Create Virtual Mailboxes on CentOS/RHEL Mail Server
This tutorial is going to show you how to create virtual mailboxes on CentOS/RHEL mail server with PostfixAdmin, which is an open-source web-based interface to configure and manage a Postfix based email server for many domains and users.
PostfixAdmin – Create Virtual Mailboxes on CentOS/RHEL Mail Server