added domain alias support

postfix/config/main.cf

 virtual_mailbox_maps = pgsql:/etc/postfix/pgsql_virtual_mailbox_maps.cf
 virtual_alias_maps = pgsql:/etc/postfix/pgsql_virtual_alias_maps.cf,
                      pgsql:/etc/postfix/pgsql_virtual_alias_maps_regexp.cf,
+                     pgsql:/etc/postfix/pgsql_virtual_alias_domain_maps.cf,
                      pgsql:/etc/postfix/pgsql_virtual_alias_maps_alias.cf
 relay_domains = pgsql:/etc/postfix/pgsql_relay_domains.cf
 virtual_minimum_uid=100

postfix/config/pgsql_virtual_alias_domain_maps.cf

+hosts = POSTGRES_HOST
+user = POSTGRES_USER
+password = POSTGRES_PASSWORD
+dbname = POSTGRES_DB
+query = SELECT a.goto FROM alias_domain ad LEFT JOIN alias a ON a.domain = ad.target_domain WHERE ad.alias_domain = '%d' AND ad.active = true AND a.address = '%u' || '@' || ad.target_domain

postfix/vars-files

 /etc/postfix/pgsql_relay_domains.cf
 /etc/postfix/pgsql_transport.cf
 /etc/postfix/pgsql_virtual_alias_maps_alias.cf
+/etc/postfix/pgsql_virtual_alias_domain_maps.cf
 /etc/postfix/pgsql_virtual_alias_maps.cf
 /etc/postfix/pgsql_virtual_alias_maps_regexp.cf
 /etc/postfix/pgsql_virtual_mailbox_domains.cf