Hi, im thinking how to improve my website / service. So is it good idea to add some survey box ("tell your oppinion" box) when visitor closing my website? Maybe it would be better to place input box on the website, but how to protect it from spam and keeping it space savy?

Maybe some feedback bubble to appear when visitor closing Tab:
Are You missing anything? and text box + email box + send button

UserVoice.com shows floating button for user feedback, but i cant see if it allows form to appear on browser Tab close