# /etc/postfix/mysql_virtual_alias_domainaliases_maps.cf

user = mail
password = **password**
hosts = 127.0.0.1
dbname = mail
query = SELECT goto FROM alias,alias_domain
  WHERE alias_domain.alias_domain = '%d'
  AND alias.address=concat('%u', '@', alias_domain.target_domain)
  AND alias.active = 1

# /etc/postfix/mysql_virtual_alias_maps.cf

user = mail
password = **password**
hosts = 127.0.0.1
dbname = mail
table = alias
select_field = goto
where_field = address
additional_conditions = and active = '1'

# /etc/postfix/mysql_virtual_domain_maps.cf

user = mail
password = **password**
hosts = 127.0.0.1
dbname = mail
table = domain
select_field = domain
where_field = domain
additional_conditions = and backupmx = '0' and active = '1'

# /etc/postfix/mysql_virtual_mailbox_domainaliases_maps.cf

user = mail
password = **password**
hosts = 127.0.0.1
dbname = mail
query = SELECT maildir FROM mailbox, alias_domain
  WHERE alias_domain.alias_domain = '%d'
  AND mailbox.username=concat('%u', '@', alias_domain.target_domain )
  AND mailbox.active = 1

# /etc/postfix/mysql_virtual_mailbox_maps.cf

user = mail
password = **password**
hosts = 127.0.0.1
dbname = mail
table = mailbox
select_field = CONCAT(domain, '/', local_part)
where_field = username
additional_conditions = and active = '1'