Here is my postconf -n
alias_maps = hash:/etc/aliases
append_dot_mydomain = no
biff = no
command_directory = /usr/sbin
config_directory = /etc/postfix
daemon_directory = /usr/libexec/postfix
data_directory = /var/lib/postfix
header_checks = regexp:/etc/postfix/header_checks
html_directory = no
inet_protocols = ipv4
local_transport = error:local delivery is disabled
mail_owner = postfix
mailbox_size_limit = 0
mailq_path = /usr/bin/mailq.postfix
manpage_directory = /usr/share/man
message_size_limit = 52428800
mydestination = mailgate15.slac.stanford.edu, mailgate15,
localhost.localdomain, localhost, localhost.slac.stanford.edu, smtpout,
smtpout.slac.stanford.edu
mydomain = slac.stanford.edu
myhostname = mailgate15.slac.stanford.edu
mynetworks = 127.0.0.0/8 134.79.0.0/16 172.16.0.0/12
myorigin = slac.stanford.edu
newaliases_path = /usr/bin/newaliases.postfix
queue_directory = /var/spool/postfix
readme_directory = /usr/share/doc/postfix-2.10.1/README_FILES
relayhost = mxa-00000d04.gslb.pphosted.com
remote_header_rewrite_domain = slac.stanford.edu
sample_directory = /usr/share/doc/postfix-2.10.1/samples
sendmail_path = /usr/sbin/sendmail.postfix
setgid_group = postdrop
smtp_sasl_auth_enable = no
smtp_tls_CAfile = /etc/postfix/ca.crt
smtp_tls_ciphers = high
smtp_tls_exclude_ciphers = EXP, MEDIUM, LOW, DES, 3DES, SSLv2, RC4, aNULL
smtp_tls_loglevel = 2
smtp_tls_mandatory_protocols = !SSLv2,!SSLv3
smtp_tls_protocols = !SSLv2,!SSLv3
smtp_tls_security_level = may
smtp_tls_session_cache_database = btree:${data_directory}/smtp_scache
smtp_use_tls = yes
smtpd_client_restrictions = permit_mynetworks,permit_sasl_authenticated,
reject_non_fqdn_helo_hostname,permit
smtpd_tls_CAfile = /etc/postfix/ca.crt
smtpd_tls_cert_file = /etc/postfix/smtpout_slac_stanford_edu.crt
smtpd_tls_ciphers = high
smtpd_tls_exclude_ciphers = EXP, MEDIUM, LOW, DES, 3DES, SSLv2, RC4, aNULL
smtpd_tls_key_file = /etc/postfix/smtpout_slac_stanford_edu.key
smtpd_tls_loglevel = 2
smtpd_tls_mandatory_protocols = !SSLv2,!SSLv3
smtpd_tls_protocols = !SSLv2,!SSLv3
smtpd_tls_received_header = yes
smtpd_tls_session_cache_database = btree:${data_directory}/smtpd_scache
smtpd_use_tls = yes
tls_high_cipherlist =
kEECDH:+kEECDH+SHA:kEDH:+kEDH+SHA:+kEDH+CAMELLIA:kECDH:+kECDH+SHA:kRSA:+kRSA+SHA:+kRSA+CAMELLIA:!aNULL:!eNULL:!SSLv2:!RC4:!MD5:!DES:!EXP:!SEED:!IDEA:!3DES
tls_medium_cipherlist =
kEECDH:+kEECDH+SHA:kEDH:+kEDH+SHA:+kEDH+CAMELLIA:kECDH:+kECDH+SHA:kRSA:+kRSA+SHA:+kRSA+CAMELLIA:!aNULL:!eNULL:!SSLv2:!MD5:!DES:!EXP:!SEED:!IDEA:!3DES
-----Original Message-----
From: owner-postfix-us...@postfix.org <owner-postfix-us...@postfix.org> On
Behalf Of Wietse Venema
Sent: Thursday, January 28, 2021 1:00 PM
To: Postfix users <postfix-users@postfix.org>
Subject: Re: Trouble with STARTTLS...Connection lost
Chu, Uy:
> Hi All,
>
> I am having trouble with one of our application server not being able to
> connect to send emails. I noticed the issue of connection lost after
> STARTTLS. Is it a configuration on the SMTP server or the application?
>
"postconf -n" output please?
Wietse
