When Adobe Reader or Acrobat is deployed in the enterprise with enhanced security turned on, warnings appear in the client. The warnings appear when Acrobat tries to merge data in a PDF.
Define the sites that host the PDF and data files as trusted. The Windows trusted sites list is maintained under the following registry key:
HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Internet Settings\Zone Map\Domains
These warnings are data-injection warnings and react according to the Internet security settings under Windows > Control Panel > Internet Settings > Security. Or, to the enhanced security settings under Reader > Preferences > Enhanced Security. Many large organizations define sites that host PDF and data files as trusted when they do not want their users confronted with warning messages.
You can define the trusted sites manually in Reader or Windows. However, most organizations need an automated way to define these hosts during the installation routines.