How to make a simple database schema for my Postfix email server?

Question

Email

Setting up Postfix for my soap. I can't figure out the database schema for MySql or Postgresql. Everywhere they write differently.
What tables do I *need* to make my own simple gmail that will serve a dozen domains and a hundred users?
I understand that
1) Wirth. domains (name)
2) Wirth. users(name/email, domain_id, passw)
3) aliases/forwardings(from_full_email, to_full_email)?
Everything?
Please do not offer me postfixadmin

Answer 1

It's more than enough

Answer 2

So you can not bother with databases at all, but use files for this. IMHO it's easier.