Answer
The option for SMTP authentication in the GFI FaxMaker Fax Message Form is only available for Microsoft Windows XP / Microsoft Windows Server 2000 or higher. However, this feature is not available for older versions of the Microsoft operating system (e.g. Microsoft Windows 9x, Microsoft Windows ME or Microsoft Windows Server NT).
This is because the SMTP authentication feature requires the usage of the Microsoft Collaboration Data Objects (CDO), which are only available for those platforms.