安装OpenSSL

重新编译安装postfix以支持tls

生成并安装证书

编辑main.cf, 设定TLS参数

# TLS parameters

smtpd_use_tls = yes

smtpd_tls_cert_file=/etc/ssl/certs/ssl-cert-snakeoil.pem

smtpd_tls_key_file=/etc/ssl/private/ssl-cert-snakeoil.key

smtpd_tls_CAfile=/etc/ssl/private/ssl-cacert-snakeoil.key

smtpd_tls_session_cache_database = btree:${queue_directory}/smtpd_scache

smtp_tls_session_cache_database = btree:${queue_directory}/smtp_scache

重新加载postfix