I log into https://www.masterbranch.com and it has this option to link my stackoverflow user, but it ask me to type my email ( probably just to avoid me pointint to Jon's )
I type some random email for I don't want them to have my email but they notice it wasn't the one I use in SO.
How could they?
My guess, is they fetch the gravatar from stackoverflow and the gravatar from the email I type, but I don't really know if that makes sense.
Is there a security hole in StackOverflow?