Email address of accounts?

[Cuban]

Hello everyone. I was wondering something today. Is there any way possible to find the email address of an account on any forum/website? Like for example, if I go to newgrounds.com and search up a user, how would I check his email. I don't want or need the password of these accounts I just want to know the email. Is this possible? If it is then someone please reply or PM me because this would be awesome. Thank you for your time.