Как отправить зашифрованное сообщение с помощью постфикса?

У меня есть приложение на убунту 18.4 vps. я могу отправлять письма, используя постфикс но Gmail говорит, что он не зашифрован. Файл конфигурации postfix:

# See /usr/share/postfix/main.cf.dist for a commented, more complete version


# Debian specific:  Specifying a file name will cause the first
# line of that file to be used as the name.  The Debian default
# is /etc/mailname.
#myorigin = /etc/mailname

smtpd_banner = $myhostname ESMTP $mail_name (Ubuntu)
biff = no

# appending .domain is the MUA's job.
append_dot_mydomain = no

# Uncomment the next line to generate "delayed mail" warnings
#delay_warning_time = 4h

readme_directory = no

# See http://www.postfix.org/COMPATIBILITY_README.html -- default to 2 on
# fresh installs.
compatibility_level = 2

# TLS parameters
smtpd_tls_cert_file = /home/avanel/CMS/Render/ipeccongress_com.crt
smtpd_tls_key_file = /home/avanel/CMS/Render/capk.txt
smtpd_use_tls=yes
smtpd_tls_session_cache_database = btree:${data_directory}/smtpd_scache
smtp_tls_session_cache_database = btree:${data_directory}/smtp_scache

# See /usr/share/doc/postfix/TLS_README.gz in the postfix-doc package for
# information on enabling SSL in the smtp client.

smtpd_relay_restrictions = permit_mynetworks permit_sasl_authenticated defer_unauth_destination
alias_maps = hash:/etc/aliases
alias_database = hash:/etc/aliases
myorigin = $mydomain
mydestination = $myhostname, localhost.$mydomain, $mydomain
mynetworks = 127.0.0.0/8 [::ffff:127.0.0.0]/104 [::1]/128
mailbox_command = procmail -a "$EXTENSION"
mailbox_size_limit = 0
recipient_delimiter = +
inet_protocols = all
mynetworks_style = subnet
smtpd_sasl_auth_enable = yes
smtp_sasl_password_maps=hash:/etc/postfix/sasl_passwd 
smtp_sasl_security_options=


smtpd_tls_security_level = may
smtp_tls_security_level = may
smtp_tls_loglevel = 1
smtpd_tls_loglevel = 1

smtp_tls_CAfile=/home/avanel/CMS/Render/tl.ca-bundle

теперь что не так?