This policy setting controls whether Office 2013 applications notify users about unsafe hyperlinks. Links that Office 2013 ...

This policy setting controls whether Office 2013 applications notify users about unsafe hyperlinks.  Links that Office 2013 considers unsafe include links to executable files, TIFF files, and Microsoft Document Imaging (MDI) files. Other unsafe links are those that use protocols considered to be unsafe such as javascript. If you enable this policy setting, unsafe hyperlink warnings are suppressed for all users. If you disable or do not configure this policy setting, hyperlink warnings cannot be suppressed by any means. Office 2013 users will be notified that links are unsafe and must enable them manually to use them.