This extension simply allows you to click on the name of the sender in an open gmail email in order to copy the email of the sender. When you click on the name of the sender it automatically changes the text to the senders email and highlights it. Then after you press crtl-c or command-c, it will revert back to the original text.
I built this because I found myself constantly hovering over the user's name, highlighting their email, and then copying it. THis is much easier.