Why is a record with my domain created when creating\importing mail contacts from csv?

Question

PowerShell

When creating a new mail contact manually or when exporting contacts from cvs using powershell, an additional one is created. mailbox in my domain. For example, when creating a contact [email protected], [email protected] is also created:

Moreover, if I take and delete the box with my domain and save the changes, then the next time the contact is opened, the box will be there again.
What is it for and is it necessary at all? Because when exporting more than 3000 contacts from a csv file, the same number of mailboxes are created in my domain with that name.
Exchange 2016 version

Answer 1

The address is assigned by the email address policy