That’s going to be your aliases. Go to /etc/postfix/generic and edit it. It’s going to have a bunch of commented lines. Go to the bottom and do:
[email protected] [email protected]
asterisk [email protected]
root [email protected]
[email protected] would be your SMTP email you need to use. And you can add other system aliases if needed but that should cover it. When done do
postfix stop && postfix start from the system cli.