If you have workspaces, you can add additional branding domains.
Go to Admin and click Email.
Click Add to add an additional branding domain.
Enter a new branding domain. Click Next.
You can choose to make this your Primary Domain for one or more workspaces, and all existing unsent emails set to “Default” and all newly created emails will default to the primary domain. You can override this on a per-email basis.
Select the new branding domain and click Save.