smtpd_recipient_restrictions =
        reject_invalid_hostname,
        reject_unknown_recipient_domain,
        reject_unauth_pipelining,
        permit_sasl_authenticated,
        permit_mynetworks,
        reject_unauth_destination,
        reject_rbl_client zen.spamhaus.org,
        reject_rbl_client bl.spamcop.net,
        reject_rbl_client dnsbl.sorbs.net,
        reject_rbl_client cbl.abuseat.org,
        reject_rbl_client b.barracudacentral.org,
        reject_rbl_client dnsbl-1.uceprotect.net,
        check_policy_service unix:private/policy-spf