The majority of IIS installations do not require SMTP service to be installed, but specific web applications may require it. If this is the case, you should set the Smart Host to be  smarthost.cc.ic.ac.uk.

1. Open the Internet Information Services Management Console.

2. Right click on the SMTP Service.

3. Click Properties.

4. Select the Delivery tab and click on the Advanced button.

5. Enter smarthost.cc.ic.ac.uk into the Smart Host section.

IIS smart host settings