Postfix Mail Errors

Hello I am getting errror: address resolver failure error in my webmin when i am trying to send the mal from my mac Osx 10.14.6. I have installed virtualmin 6.08 GPL on my server. I have done everything in my knowledge to resolve this error. but its not getting resolved. I you want to look a my main.cf file then have a lookL:
Postfix/main.cf:

smtpd_helo_required = yes

#smtpd_pw_server_security_options = cram-md5,digest-md5

#content_filter = smtp-amavis:[127.0.0.1]:10024

#receive_override_options = no_address_mappings

smtpd_sasl_auth_enable = yes

smtp_tls_cert_file = /private/etc/letsencrypt/live/space69.4elements-hosting.cloud/fullchain.pem

smtp_tls_key_file = /private/etc/letsencrypt/live/space69.4elements-hosting.cloud/privkey.pem

smtpd_tls_cert_file = /private/etc/letsencrypt/live/space69.4elements-hosting.cloud/fullchain.pem

smtpd_tls_key_file = /private/etc/letsencrypt/live/space69.4elements-hosting.cloud/privkey.pem

smtpd_recipient_restrictions = permit_sasl_authenticated check_client_access hash:/usr/local/etc/postfix/client_checks check_sender_access
hash:/usr/local/etc/postfix/sender_checks reject_unauth_destination check_policy_service inet:127.0.0.1:10029 permit_mynetworks

smtpd_helo_restrictions = reject_non_fqdn_helo_hostname reject_invalid_helo_hostname

smtpd_enforce_tls = yes

smtpd_use_tls = yes

#myhostname = space69.4elements-hosting.cloud

#smtpd_use_pw_server = yes

header_checks = pcre:/usr/local/etc/postfix/custom_header_checks

recipient_canonical_maps = hash:/usr/local/etc/postfix/system_user_maps

postscreen_dnsbl_sites = zen.spamhaus.org*2 bl.spamcop.net sbl-xbl.spamhaus.org cbl.abuseat.org psbl.surriel.com

mydestination = $myhostname, localhost.$mydomain, localhost, $mydomain

mailbox_transport = dovecot

#mydomain = 4elements.cloud

virtual_alias_maps = $virtual_maps hash:/usr/local/etc/postfix/virtual_users

mydomain = 4elements-hosting.cloud

virtual_alias_domains = $virtual_maps hash:/usr/local/etc/postfix/virtual_domains

smtpd_tls_security_level = may

smtpd_tls_loglevel = 1

smtp_sasl_password_maps =

mynetworks_style = subnet

meta_directory = /usr/local/etc/postfix

shlib_directory = no

body_checks = pcre:/usr/local/etc/postfix/body_checks

mail_spool_directory = /usr/local/Mail/Data/mail

append_dot_mydomain = yes

smtpd_relay_restrictions = ${{$compatibility_level} < {1} ? {} : {permit_mynetworks permit_sasl_authenticated defer_unauth_destination}} permit_mynetworks

smtp_sasl_type = dovecot

smtpd_sasl_path = private/auth

Any help will be very much appreciated.