Let’s have another snippet of Run Your Own Mail Server.
Text file configuration works great for settings that rarely change. If your mail server is truly only for you, then text files will probably be fine. When you have a larger number of users or a more dynamic environment, however, you need easier management. That means a database. And a front end to manage that database, because routinely running raw SQL commands would require memorizing the database structure and that would consume brain space better utilized for something else. Anything else.
Many folks have written database-driven Postfix management systems. Some of them are even adequate. This book will use PostfixAdmin (https://postfixadmin.github.io/postfixadmin/), but primarily to illustrate database-backed Postfix and Dovecot. We won’t go through the web interface, because web interfaces frequently change and once you’ve managed Postfix via text files your most common question is “where did they hide the option for this setting?”
Running your own mail server requires sysadmin expertise. You should probably read some of my other books before trying it.