Mail server

What does a Unix mail server do with mail it receives that isn't to any users on it?

Is there a way to setup a list (one that contains a list of E-mail addresses and where to forward them) that the mail server checks then forwards E-mail it receives even though it isn't to any user on it?


if your useing sendmail check


# Test mail address to these people to mimic an external trading partner,,

now lets test.

echo This is a test email for the 3 people in my list|mailx -s "Testing Aliases" external

and all 3 people would get the mail.