postfix - webmail - 530 5.7.57 SMTP; Client was not authenticated to send anonymous mail

Hi,

I’m trying to send emails from our SUSE linux 15 SP 0 system.
I configured postfix as per https://www.suse.com/support/kb/doc/?id=000019344.
However, I’m getting this error when trying to send emails:

“postfix/smtp[66616]: 3BF3C60A1D: to=email@client.com, relay=webmail.client.com[172.29.IP.IP]:587, delay=5, delays=0/0/0.01/5, dsn=5.7.57, status=bounced (host webmail.client.com[172.29.IP.IP] said: 530 5.7.57 SMTP; Client was not authenticated to send anonymous mail during MAIL FROM (in reply to MAIL FROM command))”

My postconf config:

postconf -n

alias_maps = hash:/etc/aliases
biff = no
canonical_maps = hash:/etc/postfix/canonical
command_directory = /usr/sbin
compatibility_level = 2
content_filter =
daemon_directory = /usr/lib/postfix/bin/
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
defer_transports =
delay_warning_time = 1h
disable_dns_lookups = no
disable_mime_output_conversion = no
disable_vrfy_command = yes
html_directory = /usr/share/doc/packages/postfix-doc/html
inet_interfaces = localhost
inet_protocols = all
mail_owner = postfix
mail_spool_directory = /var/mail
mailbox_command =
mailbox_size_limit = 0
mailbox_transport =
mailq_path = /usr/bin/mailq
manpage_directory = /usr/share/man
masquerade_classes = envelope_sender, header_sender, header_recipient
masquerade_domains =
masquerade_exceptions = root
message_size_limit = 0
message_strip_characters = \0
mydestination = $myhostname, localhost.$mydomain
myhostname = client_hostname.workplace.local
mynetworks_style = subnet
newaliases_path = /usr/bin/newaliases
queue_directory = /var/spool/postfix
readme_directory = /usr/share/doc/packages/postfix-doc/README_FILES
relay_clientcerts =
relay_domains = $mydestination, hash:/etc/postfix/relay
relayhost = [webmail.client.com]:587
relocated_maps = hash:/etc/postfix/relocated
sample_directory = /usr/share/doc/packages/postfix-doc/samples
sender_canonical_maps = hash:/etc/postfix/sender_canonical
sendmail_path = /usr/sbin/sendmail
setgid_group = maildrop
smtp_enforce_tls = no
smtp_sasl_auth_enable = yes
smtp_sasl_password_maps = hash:/etc/postfix/sasl_passwd
smtp_sasl_security_options = noanonymous
smtp_sasl_tls_security_options = noanonymous
smtp_tls_CAfile =
smtp_tls_CApath =
smtp_tls_cert_file =
smtp_tls_key_file =
smtp_tls_session_cache_database =
smtp_use_tls = yes
smtpd_banner = $myhostname ESMTP
smtpd_client_restrictions =
smtpd_delay_reject = yes
smtpd_helo_required = no
smtpd_helo_restrictions =
smtpd_recipient_restrictions = permit_mynetworks,reject_unauth_destination
smtpd_sender_restrictions = hash:/etc/postfix/access
smtpd_tls_CAfile =
smtpd_tls_CApath =
smtpd_tls_ask_ccert = no
smtpd_tls_cert_file =
smtpd_tls_key_file =
smtpd_tls_received_header = no
smtpd_use_tls = no
strict_8bitmime = no
strict_rfc821_envelopes = no
transport_maps = hash:/etc/postfix/transport
unknown_local_recipient_reject_code = 550
virtual_alias_domains = hash:/etc/postfix/virtual

Kindly assist?
Kind Regards,