I'm trying to configure a basic postfix server to allow receipt of email from anywhere to local addresses but not be an open relay.
Current config, seemingly relevant rules:
mydestination = $myhostname, localhost.$mydomain, localhost mynetworks = 0.0.0.0/0 relay_domains = $mydestination
If I change mynetworks back to 127.0.0.1/8 it doesn't receive external mail. Leaving relay_domains blank seems to make no difference and keeps this as an open relay.
What am I missing?