smtpd_helo_required = yes
disable_vrfy_command = yes
strict_rfc821_envelopes = yes
smtpd_etrn_restrictions = reject

smtpd_helo_restrictions =
        permit_sasl_authenticated,
        permit_mynetworks,
        reject_invalid_hostname,
        reject_non_fqdn_hostname

smtpd_sender_restrictions =
        reject_unknown_sender_domain,
        reject_non_fqdn_sender

smtpd_recipient_restrictions =
        reject_invalid_hostname,
        reject_non_fqdn_hostname,
        reject_non_fqdn_sender,
        reject_non_fqdn_recipient,
        reject_unknown_sender_domain,
        reject_unknown_recipient_domain,
        permit_sasl_authenticated,               
        permit_mynetworks,
        reject_unauth_destination

smtpd_data_restrictions = reject_unauth_pipelining