An alias translates an email address into one or more destination addresses. Windows users may understand this concept as a "distribution list." You can add an alias as a convenient shortcut for typing a long list of recipients. An alias can also translate addresses from one top-level domain to another.
Address masquerading is a method of concealing email addresses or domain names behind the mail gateway by assigning replacement values to them.
Review examples of alias source and destination addresses.
You can enter multiple destination email addresses for each alias that you enter as a source email address. You can only enter a single destination domain, however, for each alias that you enter as a source domain. Alias source addresses must have local domains. Destination domains can be local or non-local domains.