Add a (not working) postfix conf for transports

postfix/conf/main.cf

@@ -90,7 +90,8 @@ virtual_alias_maps = ${sql}sqlite-virtual_alias_maps.cf
 virtual_mailbox_domains = ${sql}sqlite-virtual_mailbox_domains.cf
 virtual_mailbox_maps = $virtual_alias_maps
 
-# Mails are forwarded to Dovecot for delivery
+# Mails are transported if required, then forwarded to Dovecot for delivery
+transport_maps = ${sql}sqlite-transport.cf
 virtual_transport = lmtp:inet:imap:2525
 
 # In order to prevent Postfix from running DNS query, enforce the use of the

postfix/conf/sqlite-transport.cf

@@ -0,0 +1,3 @@
+dbpath = /data/main.db
+query =
+  SELECT 'smtp:'||smtp FROM relay WHERE name='%s'