Tenés mal configurado la parte de TLS del postfix.
Usa esta configuración, igualmente adaptándola a tu entorno:
Código:
biff = no
append_dot_mydomain = no
alias_maps = hash:/etc/aliases
alias_database = hash:/etc/aliases
mailbox_command = procmail -a "$EXTENSION"
mailbox_size_limit = 0
recipient_delimiter = +
inet_protocols = all
smtpd_sasl_local_domain =
smtpd_sasl_auth_enable = yes
smtpd_sasl_security_options = noanonymous
broken_sasl_auth_clients = yes
smtpd_tls_auth_only = no
smtp_use_tls = yes
smtp_tls_note_starttls_offer = yes
smtpd_tls_CAfile = /etc/postfix/ssl/cacert.pem
smtpd_tls_loglevel = 1
smtpd_tls_received_header = yes
smtpd_tls_session_cache_timeout = 3600s
tls_random_source = dev:/dev/urandom
myorigin = /etc/mailname
mydestination = nombre.dominio.com, localhost.localdomain, localhost, aeurus.cl
inet_interfaces = all
home_mailbox = Maildir/
relayhost =
# Adaptar estos ##########
mynetworks = 127.0.0.0/8 192.168.0.0/24
myhostname = nombre.dominio.com
#####################
fallback_relay =