Exchange 2013:
Exchange 2007/2010:
Open Exchange Management Console.
- Click on the '+' next to Organization Configuration.
- Select Hub Transport and select the 'Send Connectors' tab.
- Right-click on the existing Send Connector, select 'Properties' and go to the Network tab.
- Select "Route mail through the following smart hosts:" and click 'Add'.
Exchange 2000/2003:
Open Exchange System Manager.
- Click on the '+' next to Connectors.
- Right-click on the existing SMTP Connector, select 'Properties' and go to the General tab.
- Select "forward all mail to a smart host" and write the smart host.