Is it possible to figure out what websites a person is a member of by knowing their email address?

i know this is an odd question, but i wasn't sure if it was possible. i know the email and password, but i don't know if there is a way to search for websites they may or may not be a member to.Is it possible to figure out what websites a person is a member of by knowing their email address?
If I saw your email address, I might guess that you're a member of Yahoo.

freckles