This is a simple script that allows you to see your email associated with your riot games / league of legends account. All you have to do is install the userscript and log in here https://support.riotgames.com/hc/en-us? It must be in the support page and not in any other. There is no scam, the source code is very easy to understand so that you see I won't steal any information.
When you log in you might see an alert with your e-mail, as in the enclosed screenshot