Microsoft IIS SMTP Server Does Not Relay or Send Emails

Symptom:

You've installed the SMTP server (Default SMTP Virtual Server) as a part of the IIS on Microsoft Windows Server 2003, but nothing get relayed.

What Fixed:

The no hosts, including the local ones are by default not being relayed out of the box. You need to go to Default SMTP Virtual Server Properties, go in the Access tab and Press the Relay... button.

You should grant the relay permission to the server or all the IP addresses in your local network.

Total research fix time: About 30 minutes.