NOTE: This may not apply to your version of the cms. Please contact us if you are not sure.
The latest version of the cms give you the control of the external link and trusted partner link settings. You can edit which domains are whitelisted and the content of the warning notifications.
See this screenshot for more instructions: https://www.screencast.com/users/Manachar/folders/Jing/media/b072091c-b331-440b-9583-b33560f4d6bd.