You can alias a domain to another domain already added and configured on the Domains > Domain Settings page. When you make a domain an alias, it inherits the settings created on the parent domain.
Once you alias a domain to one or more domains already added and configured in the service, the number of configured domain aliases displays in the Domains Manager table on the Domains page. Click on the domain name to toggle the alias names. Click on a domain alias to view the inherited domain settings.