smtpd_recipient_restrictions = permit_mynetworks, permit_sasl_authenticated, reject_unauth_destination, reject_unauth_pipelining, reject_unknown_sender_domain, reject_unknown_recipient_domain

smtpd_client_restrictions = permit_mynetworks, permit_sasl_authenticated, reject_invalid_hostname, reject_rbl_client zen.spamhaus.org, reject_rbl_client bl.spamcop.net, reject_rbl_client cbl.abuseat.org

smtpd_sender_restrictions = permit_mynetworks, reject_unknown_address, reject_unknown_sender_domain, reject_non_fqdn_sender

user = emailserveruser
password = sdfjn1234ns
hosts = 127.0.0.1
dbname = mailstack
query = SELECT * FROM (SELECT email FROM `virtual_users` WHERE email = '%s' UNION SELECT destination FROM `virtual_alias` WHERE source = '%s' ) a LIMIT 1