this is a small practice of downloading a list of anonymous emails gravatar images, this could give you a good indicator of what email is active.
the script is for fun use only, i got the list of emails from pastebin
and you can use any emails list.
Full script with docs : https://github.com/blazeeboy/RubyScripts/tree/master/2014-06-24
Full script with docs : https://github.com/blazeeboy/RubyScripts/tree/master/2014-06-24