Is there a way to lock down exchange server to only accept connections from range of IPs on port 25?
We subscribed to Peer 2 Peer and have our MX records pointing at them so they will filter the email and then forward it to us.
So mail "should" only be allowed from their IP addresses.
The router is SOHO so it can not be done in the router.
And I'd like to avoid 3rd part software if possible