config in main.cf (postfix > 2.3)<\/p>\n
smtpd_client_restrictions=
\n permit_sasl_authenticated
\n reject_unknown_client_hostname
\n reject_rbl_client cblless.anti-spam.org.cn
\n reject_rbl_client zen.spamhaus.org
\n reject_rbl_client bl.spamcop.net<\/p>\n
##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).##
\nsmtpd_helo_required = yes
\nsmtpd_helo_restrictions=
\n reject_invalid_helo_hostname
\n reject_non_fqdn_helo_hostname
\n reject_unknown_helo_hostname
\n reject_rhsbl_helo dbl.spamhaus.org<\/p>\n
smtpd_sender_restrictions=
\n reject_non_fqdn_sender
\n reject_unknown_sender_domain
\n reject_rhsbl_sender dbl.spamhaus.org
\n check_sender_access hash:\/etc\/postfix\/spam-email<\/p>\n
smtpd_recipient_restrictions=
\n reject_non_fqdn_recipient
\n reject_unauth_destination
\n reject_unknown_recipient_domain
\n reject_rhsbl_recipient dbl.spamhaus.org
\n check_recipient_access hash:\/etc\/postfix\/spam-email<\/p>\n","protected":false},"excerpt":{"rendered":"