If anything was changed on the server I don't know.
The settings of the client SMTP are:
port 25
auth metod: normal password
connection security STARTTLS

This is the result of postconf

alias_database = hash:/etc/postfix/aliases
alias_maps = hash:/etc/postfix/aliases
allow_min_user = no
allow_percent_hack = no
biff = no
body_checks = pcre:/etc/postfix/body_checks.pcre
command_directory = /usr/sbin
compatibility_level = 2
content_filter = smtp-amavis:[127.0.0.1]:10024
daemon_directory = /usr/lib/postfix/sbin
data_directory = /var/lib/postfix
debug_peer_level = 2
debugger_command = PATH=/bin:/usr/bin:/usr/local/bin:/usr/X11R6/bin ddd $daemon_directory/$process_name $process_id & sleep 5
disable_vrfy_command = yes
dovecot_destination_recipient_limit = 1
enable_original_recipient = no
header_checks = pcre:/etc/postfix/header_checks
inet_interfaces = all
inet_protocols = all
lmtp_tls_mandatory_protocols = !SSLv2 !SSLv3
lmtp_tls_protocols = !SSLv2 !SSLv3
mail_owner = postfix
mailq_path = /usr/bin/mailq
message_size_limit = 20480000
mydestination = $myhostname, localhost, localhost.localdomain
mydomain = xxxx.net
myhostname = mail.xxxx.net
mynetworks = 127.0.0.1 [::1], 94.23.81.226
myorigin = mail.xxxx.net
newaliases_path = /usr/bin/newaliases
postscreen_access_list = permit_mynetworks cidr:/etc/postfix/postscreen_access.cidr
postscreen_blacklist_action = enforce
postscreen_dnsbl_action = enforce
postscreen_dnsbl_reply_map = texthash:/etc/postfix/postscreen_dnsbl_reply
postscreen_dnsbl_sites = zen.spamhaus.org=127.0.0.[2..11]*3 b.barracudacentral.org=127.0.0.[2..11]*2
postscreen_dnsbl_threshold = 2
postscreen_dnsbl_whitelist_threshold = -2
postscreen_greet_action = enforce
proxy_read_maps = $canonical_maps $lmtp_generic_maps $local_recipient_maps $mydestination $mynetworks $recipient_bcc_maps $recipient_canonical_maps $relay_domains $relay_recipient_maps $relocated_maps $sender_bcc_maps $sender_canonical_maps $smtp_generic_maps $smtpd_sender_login_maps $transport_maps $virtual_alias_domains $virtual_alias_maps $virtual_mailbox_domains $virtual_mailbox_maps $smtpd_sender_restrictions $sender_dependent_relayhost_maps
queue_directory = /var/spool/postfix
recipient_bcc_maps = proxy:mysql:/etc/postfix/mysql/recipient_bcc_maps_user.cf proxy:mysql:/etc/postfix/mysql/recipient_bcc_maps_domain.cf
recipient_delimiter = +
relay_domains = $mydestination proxy:mysql:/etc/postfix/mysql/relay_domains.cf
sender_bcc_maps = proxy:mysql:/etc/postfix/mysql/sender_bcc_maps_user.cf proxy:mysql:/etc/postfix/mysql/sender_bcc_maps_domain.cf
sender_dependent_relayhost_maps = proxy:mysql:/etc/postfix/mysql/sender_dependent_relayhost_maps.cf
sendmail_path = /usr/sbin/sendmail
setgid_group = postdrop
smtp-amavis_destination_recipient_limit = 1
smtp_tls_CAfile = $smtpd_tls_CAfile
smtp_tls_loglevel = 1
smtp_tls_mandatory_protocols = !SSLv2 !SSLv3
smtp_tls_note_starttls_offer = yes
smtp_tls_protocols = !SSLv2 !SSLv3
smtp_tls_security_level = may
smtpd_data_restrictions = reject_unauth_pipelining
smtpd_helo_required = yes
smtpd_helo_restrictions = permit_mynetworks permit_sasl_authenticated check_helo_access pcre:/etc/postfix/helo_access.pcre reject_non_fqdn_helo_hostname reject_unknown_helo_hostname
smtpd_recipient_restrictions = reject_unknown_recipient_domain reject_non_fqdn_recipient reject_unlisted_recipient check_policy_service inet:127.0.0.1:7777 permit_mynetworks permit_sasl_authenticated reject_unauth_destination reject_rbl_client zen.spamhaus.org=127.0.0.[2..11]
smtpd_reject_unlisted_recipient = yes
smtpd_reject_unlisted_sender = yes
smtpd_sasl_auth_enable = yes
smtpd_sasl_path = private/dovecot-auth
smtpd_sasl_security_options = noanonymous
smtpd_sasl_type = dovecot
smtpd_sender_login_maps = proxy:mysql:/etc/postfix/mysql/sender_login_maps.cf
smtpd_sender_restrictions = reject_unknown_sender_domain reject_non_fqdn_sender reject_unlisted_sender permit_mynetworks permit_sasl_authenticated check_sender_access pcre:/etc/postfix/sender_access.pcre
smtpd_tls_CAfile = /etc/letsencrypt/live/mail.xxxx.net/chain.pem
smtpd_tls_auth_only = yes
smtpd_tls_cert_file = /etc/letsencrypt/live/mail.xxxx.net/cert.pem
smtpd_tls_dh1024_param_file = /etc/ssl/dh2048_param.pem
smtpd_tls_dh512_param_file = /etc/ssl/dh512_param.pem
smtpd_tls_exclude_ciphers = aNULL, eNULL, EXPORT, DES, RC4, MD5, PSK, aECDH, EDH-DSS-DES-CBC3-SHA, EDH-RSA-DES-CDC3-SHA, KRB5-DE5, CBC3-SHA
smtpd_tls_key_file = /etc/letsencrypt/live/mail.xxxx.net/privkey.pem
smtpd_tls_loglevel = 1
smtpd_tls_mandatory_protocols = !SSLv2 !SSLv3
smtpd_tls_protocols = !SSLv2 !SSLv3
smtpd_tls_security_level = may
swap_bangpath = no
tls_random_source = dev:/dev/urandom
transport_maps = proxy:mysql:/etc/postfix/mysql/transport_maps_user.cf proxy:mysql:/etc/postfix/mysql/transport_maps_domain.cf
unknown_local_recipient_reject_code = 550
virtual_alias_domains =
virtual_alias_maps = proxy:mysql:/etc/postfix/mysql/virtual_alias_maps.cf proxy:mysql:/etc/postfix/mysql/domain_alias_maps.cf proxy:mysql:/etc/postfix/mysql/catchall_maps.cf proxy:mysql:/etc/postfix/mysql/domain_alias_catchall_maps.cf
virtual_gid_maps = static:2000
virtual_mailbox_base = /var/vmail
virtual_mailbox_domains = proxy:mysql:/etc/postfix/mysql/virtual_mailbox_domains.cf
virtual_mailbox_maps = proxy:mysql:/etc/postfix/mysql/virtual_mailbox_maps.cf
virtual_minimum_uid = 2000
virtual_transport = dovecot
virtual_uid_maps = static:2000