Mail domain aliases allow you to create an alias domain that is functionally identical to an existing mail domain without having to create and manage individual settings as you would for a new mail domain. Aliases are a simple way to add domains that will have identical settings to an existing mail domain.
To learn more about mail domain aliases, see its documentation page:
To configure mail domain aliases, log in to the account control center and go to:
Mail domain aliases are available immediately at no extra charge.