>> So I should specify smtpd_client_restrictions or >> smtpd_recipient_restrictions, but not both? >> > > I think most people find it easier to put all of the restrictions under > smtpd_recipient_restrictions, since you can just read them top-to-bottom > with smtpd_delay_reject = yes (the default). > > But no, you probably wouldn't need it in both places unless you had some > default restrictions you wanted to override in both places.
I've boiled my config down to this. It is functional and I think it is secure and that it rejects any attempt to send messages from outside mynetworks unless authenticated. Am I correct? Please consider all other directives to be default. master.cf: submission inet n - n - - smtpd -o smtpd_tls_security_level=encrypt -o smtpd_sasl_auth_enable=yes main.cf: smtpd_tls_security_level = may smtpd_tls_auth_only = yes smtpd_recipient_restrictions = permit_mynetworks, permit_sasl_authenticated, reject_unauth_destination, permit - Grant