Postfix: adding TLS traffic encryption support

gistfile1.txt

#add certificate
openssl req -new -nodes -x509 -out /etc/postfix/smtpd.pem -keyout /etc/postfix/smtpd.pem -days 3650

#/etc/postfix/main.cf
smtp_use_tls = yes
smtpd_use_tls = yes
smtpd_tls_auth_only = yes
smtp_tls_note_starttls_offer = yes
smtpd_tls_key_file = /etc/postfix/smtpd.pem
smtpd_tls_cert_file = /etc/postfix/smtpd.pem
smtpd_tls_CAfile = /etc/postfix/smtpd.pem
smtpd_tls_loglevel = 1
smtpd_tls_received_header = yes
smtpd_tls_session_cache_timeout = 3600s
tls_random_source = dev:/dev/urandom

#uncomment in /etc/postfix/master.cf 
#smtps inet n - n - - smtpd -o smtpd_tls_wrappermode=yes -o smtpd_sasl_auth_enable=yes

#restart postfix
postfix reload