master.cf:


smtp      inet  n       -       n       -       -       smtpd
submission inet n       -       n       -       -       smtpd
  -o smtpd_sasl_auth_enable=yes
  -o smtpd_client_restrictions=permit_sasl_authenticated,reject


Don't forget main.cf:

smtpd_tls_cert_file = /etc/postfix/TLS/somecert.pem
smtpd_tls_key_file = /etc/postfix/TLS/somecert.norsa.pem
smtpd_use_tls = yes