Open the Internet Information Services (IIS) Manager from Start> Administrative Tools. Additionally, this can be found in Control Panel, Administrative Tools
Note: On Microsoft Windows Server 2008 or later, select the Internet Information Services (IIS) 6.0 Manager
Right Click the SMTP Virtual Server and select Properties
Navigate to the 'Access' Tab and select the Relay... button
Ensure that the IP address(es) of the sending parties are added to the relay allowances. If using GFI FaxMaker with a hosted mail solution, your Mail Server's IP address(es) should be added here.
After making any edits to the SMTP settings, navigate to Command Prompt and type "iisreset" (no quotes), then hit enter. Start> run> cmd> iisreset> enter