Thanks guys. My relay server has been upgraded to 2.7.2 and smtp server to 2.4.13
inet_protocols = all <---- Had to add this due to some SPF records now using ip6: entries reject_sender_login_mismatch before permit_sasl_authenticated <--- Results in the following unwanted result: Jan 22 14:30:32 smtp1 postfix/smtpd[8000]: NOQUEUE: reject: RCPT from unknown[92.11.56.77]: 553 5.7.1 <u...@example.com>: Sender address rejected: not owned by user u...@example.com; from=<u...@exmaple.com> to=<recipi...@destination.com> proto=ESMTP helo=<GENERIC> Below are the current postconf -n for both servers. SMTP: alias_maps = anvil_rate_time_unit = 180s body_checks = regexp:/etc/postfix/body_checks bounce_size_limit = 1500 broken_sasl_auth_clients = yes config_directory = /etc/postfix default_destination_concurrency_limit = 5 disable_vrfy_command = yes header_checks = regexp:/etc/postfix/header_checks initial_destination_concurrency = 5 local_destination_concurrency_limit = 5 local_transport = error:local mail delivery disabled maximal_backoff_time = 90m message_size_limit = 14500000 mydomain = smtp1.example.net myhostname = smtp1.example.net mynetworks = 127.0.0.0/8 myorigin = example.net relocated_maps = hash:/etc/postfix/relocated smtpd_data_restrictions = reject_multi_recipient_bounce smtpd_error_sleep_time = 0 smtpd_etrn_restrictions = reject smtpd_helo_required = yes smtpd_recipient_restrictions = permit_sasl_authenticated reject_unauth_destination reject_non_fqdn_recipient reject_non_fqdn_sender reject_unlisted_recipient reject_invalid_hostname reject_unknown_sender_domain reject_unknown_recipient_domain smtpd_reject_unlisted_sender = yes smtpd_sasl_auth_enable = yes smtpd_sasl_local_domain = $myhostname smtpd_sender_login_maps = mysql:/etc/postfix/sql/relay_recipient_map.conf smtpd_sender_restrictions = check_policy_service inet:127.0.0.1:10031 permit_sasl_authenticated reject_unauth_destination reject_non_fqdn_recipient reject_non_fqdn_sender reject_unlisted_recipient reject_invalid_hostname reject_unknown_sender_domain smtpd_tls_CAfile = /usr/share/ssl/certs/ca-bundle.crt smtpd_tls_cert_file = /etc/postfix/certs/smtp1.example.net.cert smtpd_tls_key_file = /etc/postfix/certs/smtp1.example.net.key 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 transport_maps = hash:/etc/postfix/transport 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 RELAY: anvil_rate_time_unit = 180s body_checks = regexp:/etc/postfix/body_checks bounce_size_limit = 1500 broken_sasl_auth_clients = yes config_directory = /etc/postfix disable_vrfy_command = yes header_checks = regexp:/etc/postfix/header_checks inet_protocols = all local_transport = error:local mail delivery disabled maximal_backoff_time = 90m message_size_limit = 14500000 mydomain = mx11.example.net myhostname = mx11.example.net mynetworks = 127.0.0.0/8 myorigin = example.net 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 smtpd_data_restrictions = reject_multi_recipient_bounce reject_unauth_pipelining smtpd_error_sleep_time = 0 smtpd_helo_required = yes smtpd_helo_restrictions = permit_mynetworks reject_non_fqdn_hostname reject_invalid_hostname smtpd_recipient_restrictions = permit_mynetworks reject_unauth_destination 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_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:127.0.0.1:10031 check_policy_service inet:127.0.0.1:10023 smtpd_reject_unlisted_sender = yes smtpd_sasl_local_domain = $myhostname smtpd_tls_CAfile = /etc/postfix/certs/ca-bundle.crt smtpd_tls_cert_file = /etc/postfix/certs/mx11.example.net.cert smtpd_tls_key_file = /etc/postfix/certs/mx11.example.net.key 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 transport_maps = mysql:/etc/postfix/sql/relay_transport_map.conf 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
