Exchange relays settings Open the Exchange System Manager

Open the Exchange System Manager;

Go in Administrative Groups -> Administrative group name -> Server -> Server name -> Protocols -> SMTP;

Right click on Default SMTP Virtual Server -> properties;

Access tab -> Relay button;

Select “only the list bellow” and add your domain and\or IPs you do want to allow the relay

 and finally check  the “Allow all computers witch successfully authenticate to relay, regardless of the list above” checkbox.