I'm having some doubts on the receiver connector configure in our Exchange 2010, which the default receiver connector is configured to allow "Anonymous user" to connect.
We have mail gateway sitting in the DMZ zone, have 2 Exchange servers running under DAG and have no Edge transport role.
Few questions I have are:
1. Our mail gateway is connecting thru port 25, means it is connect to this default receiver connector right?
2. Do the "Anonymous user" required and why? Do mail gateways normally authenticate themselves (I can't find such settings in ours)?
3. "Anonymous user" has permission of "ms-Exch-SMTP-Accept-Any-Sender". Not sure who granted it, should it be removed or it is required in order to receive emails from external domains (from our mail gateway)?
Asking so because this connector is meant for internal relay as well. So if "anonymous user" has this permission, anyone can send as anybody, isn't this a risk to security?
Any help are greatly appreciated!