config in main.cf (postfix > 2.3)
smtpd_client_restrictions=
permit_sasl_authenticated
reject_unknown_client_hostname
reject_rbl_client cblless.anti-spam.org.cn
reject_rbl_client zen.spamhaus.org
reject_rbl_client bl.spamcop.net
##Note: specify “smtpd_helo_required = yes” to fully enforce this restriction (without “smtpd_helo_required = yes”, a client can simply skip smtpd_helo_restrictions by not sending HELO or EHLO).##
smtpd_helo_required = yes
smtpd_helo_restrictions=
reject_invalid_helo_hostname
reject_non_fqdn_helo_hostname
reject_unknown_helo_hostname
reject_rhsbl_helo dbl.spamhaus.org
smtpd_sender_restrictions=
reject_non_fqdn_sender
reject_unknown_sender_domain
reject_rhsbl_sender dbl.spamhaus.org
check_sender_access hash:/etc/postfix/spam-email
smtpd_recipient_restrictions=
reject_non_fqdn_recipient
reject_unauth_destination
reject_unknown_recipient_domain
reject_rhsbl_recipient dbl.spamhaus.org
check_recipient_access hash:/etc/postfix/spam-email