Get HTTP Referrer on Redirection

Question

How can you get the HTTP Referrer when redirected from another website, not when they click on a link since it would work for $_SERVER[\'HTTP_REFERER\'], but it

Answer 1

How can you get the HTTP Referrer when redirected from another website

You can't. If the redirection takes place under your control, you can add the original referer as a parameter, but if the external redirector doesn't do that, you have no way to get hold of the information.