To make sure our mail server is not used as an open relay, we will
smtpd_recipient_restrictions = permit_mynetworks permit_sasl_authenticated reject_unauth_destination reject_unlisted_recipient reject_unverified_recipient
You need to restart Postfix once again. After setting this up you should check if your mail server can be used as an open relay. If you have installed OSSEC for intrusion detection don't worry if the test don't finish because OSSECs active response blocks hosts that try to abuse your server (like the open relay test tool).