# client # sender # recipient # hostname smtpd_client_restrictions smtpd_sender_restrictions smtpd_recipient_restrictions smptd_helo_restrictions smtpd_data_restrictions smtpd_end_of_data_restrictions smtpd_etrn_restrictions permit_my_networks # unknown reject_unknown_client reject_unknown_client_hostname reject_unknown_reverse_client_hostname reject_unknown_helo_hostname reject_unknown_sender_domain reject_unknown_recipient_domain reject_unknown_hostname reject_non_fqdn_sender reject_non_fqdn_client reject_non_fqdn_hostname check_policy_servce reject_invalid_hostname