smtpd_helo_required = yes

# fighting spam; adapted from:
# http://dadabase.de/weblog/archives/2006/08/04/postfix-anti-spam-configuration/
# and others

# 1. client restrictions
#
#
smtpd_client_restrictions =
    permit_mynetworks,
    permit_sasl_authenticated,
    reject_invalid_hostname,
    check_client_access pcre:/etc/postfix/client-access-whitelist,
    check_client_access pcre:/etc/postfix/client-access-checks,
    reject_rbl_client dynablock.njabl.org,
    reject_rbl_client sbl-xbl.spamhaus.org,
    reject_rbl_client relays.ordb.org,
    permit

# 2. helo restrictions
#
#
smtpd_helo_restrictions =
    permit_mynetworks,
    permit_sasl_authenticated,
    reject_invalid_hostname,
    reject_non_fqdn_hostname,
    permit