I am trying to test out inbound email filtering, i have set it up in non transparent mode, the routing has my two email domains setup, routed to a static host list to the internal exchange server.
having initially had issues i set up a specific frontend receive connector on exchange
When mail comes in it get delivered. I can see from the utm mail queue that it says its queued for delivery but never gets delivered to the exchange server, i can see some emails turn up in the SMTP logs on the exchange server but don't get delivered to the mailbox.
As soon as i redirect the WAN NAT to the Exchange server mail flows properly again so its clearly interaction between the UTM and exchange