Thanks Noel. Let me know if I'm missing anything. This server is supposed to act just as a relay.
postconf -n alias_maps = anvil_rate_time_unit = 180s body_checks = regexp:/etc/postfix/body_checks bounce_size_limit = 1500 broken_sasl_auth_clients = yes command_directory = /usr/sbin config_directory = /etc/postfix daemon_directory = /usr/libexec/postfix debug_peer_level = 2 default_destination_concurrency_limit = 10 disable_vrfy_command = yes header_checks = regexp:/etc/postfix/header_checks html_directory = /var/www/html/postfix in_flow_delay = 0 inet_protocols = all initial_destination_concurrency = 10 local_destination_concurrency_limit = 10 local_recipient_maps = local_transport = error:local mail delivery disabled mail_owner = postfix mailq_path = /usr/bin/mailq manpage_directory = /usr/local/man maximal_backoff_time = 90m maximal_queue_lifetime = 5d message_size_limit = 14500000 mime_header_checks = $header_checks minimal_backoff_time = 45m mydestination = mydomain = mx.example.net myhostname = mx.example.net mynetworks = 127.0.0.0/16 myorigin = example.net nested_header_checks = newaliases_path = /usr/bin/newaliases queue_directory = /var/spool/postfix queue_run_delay = 120s readme_directory = /var/www/html/postfix relay_domains = mysql:/etc/postfix/sql/relay_transport_map.conf relay_recipient_maps = mysql:/etc/postfix/sql/relay_recipient_map.conf relocated_maps = hash:/etc/postfix/relocated sample_directory = /etc/postfix sendmail_path = /usr/sbin/sendmail setgid_group = postdrop smtp_connect_timeout = 45s smtpd_data_restrictions = reject_multi_recipient_bounce reject_unauth_pipelining smtpd_delay_reject = yes smtpd_error_sleep_time = 0 smtpd_helo_required = yes smtpd_helo_restrictions = permit_mynetworks reject_non_fqdn_hostname reject_invalid_hostname smtpd_recipient_restrictions = reject_invalid_hostname reject_non_fqdn_hostname reject_non_fqdn_sender reject_non_fqdn_recipient reject_unknown_sender_domain reject_unknown_recipient_domain reject_unlisted_recipient check_policy_service inet:127.0.0.1:10031 permit_mynetworks reject_unauth_destination check_recipient_access hash:/etc/postfix/whitelist reject_rbl_client zen.spamhaus.org reject_rbl_client b.barracudacentral.org reject_rbl_client bl.spamcop.net check_policy_service inet:127.0.0.1:10023 smtpd_reject_unlisted_sender = yes smtpd_sasl_auth_enable = no smtpd_sasl_local_domain = $myhostname smtpd_sasl_security_options = noanonymous smtpd_tls_CAfile = /etc/postfix/certs/ca-bundle.crt smtpd_tls_cert_file = /etc/postfix/certs/mx.example.net.cert smtpd_tls_key_file = /etc/postfix/certs/mx.example.net.key smtpd_tls_loglevel = 0 smtpd_tls_received_header = yes smtpd_tls_session_cache_database = btree:/etc/postfix/smtpd_scache smtpd_tls_session_cache_timeout = 7200s smtpd_use_tls = yes tls_random_source = dev:/dev/urandom transport_maps = mysql:/etc/postfix/sql/relay_transport_map.conf unknown_local_recipient_reject_code = 550 virtual_alias_maps = hash:/etc/postfix/domains/localhost hash:/etc/postfix/domains/example.com hash:/etc/postfix/domains/example.net hash:/etc/postfix/domains/example.org /etc/postfix/sql/relay_transport_map.conf user = user password = password dbname = postfix table = relay_transport_map select_field = y where_field = x query = SELECT y FROM relay_transport_map WHERE x='%s' Example: mysql> SELECT * -> FROM `relay_transport_map` -> WHERE `x` -> REGEXP CONVERT( _utf8 'enduser.com' -> USING latin1 ) -> COLLATE latin1_swedish_ci -> LIMIT 0 , 30 -> \g +--------+----------------------------+----------------+ | x | y | ip | +--------+----------------------------+----------------+ | enduser.com | cpanel:[x.x.x.x]:26 | x.x.x.x | +--------+----------------------------+----------------+ sql/relay_recipient_map.conf user = user password = password dbname = postfix query = SELECT y FROM relay_recipient_map WHERE x='%s' Example: -> SELECT * -> FROM `relay_recipient_map` -> WHERE `x` -> REGEXP CONVERT( _utf8 'enduser.com' -> USING latin1 ) -> COLLATE latin1_swedish_ci -> LIMIT 0 , 30 -> \g +----------------------------------+------+----------------+ | x | y | ip | +----------------------------------+------+----------------+ | exam...@enduser.com | OK | x.x.x.x |