Hi,
Do you have the Office 2010 Administrative Template files loaded? If so, we can find the GPO setting under:
User Configuration\Administrative Templates\Microsoft Outlook 2010\Outlook Options
Double click "Internet and network paths into hyperlinks" on the right pane and change the setting to Disabled.
In addition, we can also change the setting via modifying registry.
HKEY_CURRENT_USER\software\policies\microsoft\office\14.0\outlook\options\autoformat
DWORD: pgrfafo_25_1
Value: 1 to enable; 0 to disable
Please note, both method only configure Outlook to turn on/off the "Internet and network path into hyperlinks" setting, users can manually change the setting back then.
Best Regards,
Steve Fan
TechNet Community Support