How to create mailbox based on organization name?

Hello, experts!


There are two mail domains(Apple.com and Pear.com) and two organizations (Apple and Pear).
By default, when a new user is created, a domain primary mailbox(tomato.local) is assigned to the user, and it is also registered everywhere.

1. How to set up auto-creation of a mailbox with the desired mail domain based on the organization name?

2. How to change the default box to Exch, to the one we choose when creating a user?

Example:
Organizatios: "Pear".
Mail domain: "pear.com"
When a user (JohnSmith) is created, the default box "JohnSmith@tomato.local" is assigned to him in Exchange. It is necessary that both in Active Directory and in Exch, there is a box johnsmith@pear.com