smtpd_sender_restrictions = check_sender_access ldap:ldapcheckexternal
smtpd_restriction_classes = local_only
local_only = check_recipient_access ldap:ldapvdom, reject
smtpd_recipient_restrictions =
   check_sender_access ldap:ldap_restrictions,
   permit_sasl_authenticated,
   permit_mynetworks,
   reject_unauth_destination