For extra security you may want to disallow all use of external images or other media in instant messages, discussion messages, knowledge entries, blog posts or blog comments.
To do this go to System settings and choose the Filtering option. Now change the External content whitelisting setting to yes and select the Save button. Any <img>, <audio> or <video> HTML element in content will now only be allowed if it the site is listed in the embedded sites.
Jiglu comes with some common services enabled as embedded sites, such as YouTube. If you want to disallow their use then go to System settings and choose the Embedded sites option. Now select each site in turn, change the status to Deactivated and then select the Save button.