Configure SMTP E-Mail in IIS 7 | Microsoft Docs
docs.microsoft.com › en-us › iisMay 14, 2020 · Enable Relay for localhost: Open the Internet Information Services (IIS) 6.0 Manager. Right-click on Default SMTP Virtual Server. On the Properties page, open the Access tab, and then click on Connection. You can see which server or IP addresses are allowed to connect to the server. If the IP address 127.0.0.1 is not listed, add it using the Add button. You may also add your server IP address to the list.