postfix cannot communicate with target server via TLS/SSL

Question

I am able to connect my postfix server with TLS. All things are set up. But when i send a message with this secure connection, target server (for example gmail) receive my message without TLS/SSL secure connection.

If i use another server which has a cpanel, Gmail receive that message by ESMTP S. But when i sent a message to gmail account, it received by ESMTP (not with TLS connection.)

Sincerely, I discovered that my postfix server does not negotiate with target via SSL/TLS encrypted connection.

http://www.checktls.com reports Your email was sent, however it was NOT SENT SECURELY using TLS.

But why i am able to connect my server via TLS but server is not able to send it via secure connection?

Here is the config files:

main.cf

myhostname =  **hidden**
myorigin = /etc/mailname
mynetworks_style = host
mydestination = domains here...
relayhost =
mynetworks = 127.0.0.0/8 [::ffff:127.0.0.0]/104 [::1]/128
mailbox_size_limit = 0
recipient_delimiter = +
inet_interfaces = all
mailbox_size_limit = 0
message_size_limit = 104857600


mailbox_transport = lmtp:unix:private/dovecot-lmtp
virtual_transport = lmtp:unix:private/dovecot-lmtp

smtpd_tls_cert_file = /etc/ssl/certs/postfix.pem
smtpd_tls_key_file = /etc/ssl/private/postfix.pem

smtpd_use_tls = yes
smtpd_tls_session_cache_database = btree:${data_directory}/smtpd_scache
smtp_tls_session_cache_database = btree:${data_directory}/smtp_scache
smtpd_tls_security_level=encrypt
smtpd_tls_protocols = !SSLv2, !SSLv3
smtp_dns_support_level = enabled
smtp_tls_loglevel = 1

smtpd_sasl_type = dovecot

smtpd_sasl_path = private/auth

# and the common settings to enable SASL:
smtpd_sasl_auth_enable = yes
# With Postfix version before 2.10, use smtpd_recipient_restrictions
smtpd_relay_restrictions = permit_mynetworks, permit_sasl_authenticated, reject_unauth_destination
smtpd_recipient_restrictions = permit_mynetworks permit_inet_interfaces

append_dot_mydomain = no
readme_directory = no



smtpd_milters           = inet:127.0.0.1:8891
non_smtpd_milters       = $smtpd_milters
milter_default_action   = accept
milter_protocol     = 2

canonical_classes = header_recipient

master.cf

smtp      inet  n       -       -       -       -       smtpd
#submission inet n       -       -       -       -       smtpd
#  -o cleanup_service_name=subcleanup
#  -o smtpd_tls_security_level=encrypt
#  -o smtpd_sasl_auth_enable=yes
#  -o smtpd_client_restrictions=permit_sasl_authenticated,reject
#  -o milter_macro_daemon_name=ORIGINATING
submission inet n      -       n       -       -       smtpd
  -o syslog_name=postfix/submission
  -o smtpd_tls_wrappermode=yes
  -o smtpd_tls_security_level=encrypt
  -o smtpd_sasl_auth_enable=yes
  -o smtpd_recipient_restrictions=permit_mynetworks,permit_sasl_authenticated,reject
  -o milter_macro_daemon_name=ORIGINATING
  -o smtpd_sasl_type=dovecot
  -o smtpd_sasl_path=private/auth
smtps     inet  n       -       -       -       -       smtpd
  -o syslog_name=postfix/submission
  -o smtpd_tls_wrappermode=yes
  -o smtpd_tls_security_level=encrypt
  -o smtpd_sasl_auth_enable=yes
  -o smtpd_recipient_restrictions=permit_mynetworks,permit_sasl_authenticated,reject
  -o milter_macro_daemon_name=ORIGINATING
  -o smtpd_sasl_type=dovecot
  -o smtpd_sasl_path=private/auth

Answer 1

Enable opportunistic TLS support, i.e. send messages using TLS when the remote server identifies itself as supporting TLS, but send messages in the clear when the remote server does not :

# main.cf
smtp_tls_security_level = may

You have enabled smtpd_tls_security_level=encrypt in your config (only one letter difference), that only covers incoming e-mail traffic over SMTP, but not the outgoing email.