Conexão com o servidor IMAP interrompido durante a conexão com o Postfix + Dovecot do Outlook

Question

Bom dia a todos.
Já faz algum tempo desde que eu tenho um problema com a configuração do meu servidor de e-mail no Ubuntu Server 18.04.01 feito com o Postfix e o Dovecot. Quando tento enviar / receber e-mails do s-nail ou do Squirrelmail, nenhum problema ocorre, ao contrário do que acontece se eu tentar acessar meu servidor a partir do Outlook 2016. Quando eu tento adicionar a conta, de fato, eu logar com minhas credenciais e meus domínios e portas, chegando apenas a um carregamento infinito com as palavras "O servidor está sendo preparado ...", que inevitavelmente leva a uma conexão de erro com o servidor IMAP foi interrompido.
Para ajudar você a reconhecer o problema e recomendar uma solução, estou anexando configurações e portas:

Domínio SMTP: porta:

thenexxongroup.it:465

domínio IMAP: port:

thenexxongroup.it:993

Configuração do 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=/etc/ssl/certs/ssl-cert-snakeoil.pem
smtpd_tls_key_file=/etc/ssl/private/ssl-cert-snakeoil.key
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
myhostname = mailtest.station
alias_maps = hash:/etc/aliases
alias_database = hash:/etc/aliases
myorigin = /etc/mailname
mydestination = mailtest.station, thenexxongroup.it, mail.thenexxongroup.it, localhost.thenexxongroup.it, localhost
relayhost =
mynetworks = 127.0.0.0/8 [::ffff:127.0.0.0]/104 [::1]/128
mailbox_size_limit = 0
recipient_delimiter = +
inet_interfaces = all
inet_protocols = all
home_mailbox = Maildir/
virtual_alias_maps = hash:/etc/postfix/virtual

Configuração do Dovecot:

#verbose_proctitle = no

# Should all processes be killed when Dovecot master process shuts down.
# Setting this to "no" means that Dovecot can be upgraded without
# forcing existing client connections to close (although that could also be
# a problem if the upgrade is e.g. because of a security fix).
#shutdown_clients = yes

# If non-zero, run mail commands via this many connections to doveadm server,
# instead of running them directly in the same process.
#doveadm_worker_count = 0
# UNIX socket or host:port used for connecting to doveadm server
#doveadm_socket_path = doveadm-server

# Space separated list of environment variables that are preserved on Dovecot
# startup and passed down to all of its child processes. You can also give
# key=value pairs to always set specific settings.
#import_environment = TZ

##
## Dictionary server settings
##

# Dictionary can be used to store key=value lists. This is used by several
# plugins. The dictionary can be accessed either directly or though a
# dictionary server. The following dict block maps dictionary names to URIs
# when the server is used. These can then be referenced using URIs in format
# "proxy::<name>".

dict {
  #quota = mysql:/etc/dovecot/dovecot-dict-sql.conf.ext
  #expire = sqlite:/etc/dovecot/dovecot-dict-sql.conf.ext
}

# Most of the actual configuration gets included below. The filenames are
# first sorted by their ASCII value and parsed in that order. The 00-prefixes
# in filenames are intended to make it easier to understand the ordering.
!include conf.d/*.conf

# A config file can also tried to be included without giving an error if
# it's not found:
!include_try local.conf

mail_location=

registro de DNS:

"A" Record -> Name: "thenexxongroup.it"; IP: [Server IP]

Entrada de registro correspondente à tentativa de autenticação:

Oct  9 19:04:13 mailtest dovecot: imap-login: Disconnected: Inactivity (no auth attempts in 181 secs): user=<>, rip=[CENSORED IP], lip=192.168.1.14, TLS handshaking, session=<8fhGZ9B3AAS82nZC>