Domain name aliases are additional domain names associated with your primary domain; they function with your current set of user accounts (nicknames are not included). For instance, if you own the domains abc.com, def.com, and ghi.com, you can create a primary Google Workspace account for abc.com and add def.com and ghi.com as domain aliases to abc.com. This will help you access all emails addressed to you at both user@def.com and user@ghi.com through your user@abc.com Apps account.

You can also send mail from a domain alias.