php - How to get the HTTP_REFERER from a Yahoo or Gmail

Question

I have an e-mailer script that send messages to Yahoo or Gmail with a link on it, a link that will return back to my website when it is clicked.

I need to get the HTTP_REFERER from Yahoo or Gmail. in my site I have

echo $_SERVER["HTTP_REFERER"];

expecting something to return on it. but its empty.

Answer 1

This seems to be by design. It is possible to remove the header using Javascript shenanigans. From Google's docs on GMail privacy:

Minimized "referrer" header information. When you click on links in messages, the web browser that loads contains a referrer header. When you click on links in Gmail, Google takes steps to eliminate this referrer header, preventing others from knowing that you clicked on a link from an email.