main.cf は全体のデフォルト設定
master.cf はポートごとの上書き設定
main.cf
smtpd_sasl_auth_enable = yes smtpd_recipient_restrictions = permit_mynetworks permit_sasl_authenticated reject_unauth_destination message_size_limit = 10485760 smtpd_tls_security_level = may smtp_tls_security_level = may smtpd_tls_mandatory_protocols = !SSLv2,!SSLv3,!TLSv1,!TLSv1.1 smtp_tls_mandatory_protocols = !SSLv2,!SSLv3,!TLSv1,!TLSv1.1 smtpd_tls_cert_file=/etc/letsencrypt/live/mail.example.com/fullchain.pem smtpd_tls_key_file=/etc/letsencrypt/live/mail.example.com/privkey.pem smtpd_tls_session_cache_database = btree:/var/lib/postfix/smtpd_scache
master.cf（submission 587）
submission inet n - n - - smtpd # -o syslog_name=postfix/submission -o smtpd_tls_security_level=encrypt -o smtpd_sasl_auth_enable=yes
master.cf（smtps 465）
smtps inet n - n - - smtpd # -o syslog_name=postfix/smtps -o smtpd_tls_wrappermode=yes -o smtpd_sasl_auth_enable=yes