A way to force redirect all external links to an internal page or special redirect service.
Example:
Internal System (Instantly Redirect)
The user will be instantly redirected without any messages, additional pages, warning etc. Just redirect. Simple and clean.
Internal System (With Redirecting Page)
The user will see an internal page informing him about redirect (see the screenshots) and then be automatically redirected.
And also third party redirect services like Anon.to, Anonym.to, NullRefer.com, Redirect.am, etc...
