It depends on who you are trying to reach.
Chat with our AI personalities
Whatever email you put when you were registering.
No.
really you can use any email
There is way WAY more than just one Club Penguin email address. But if you need to contact Club Penguin, go to Community on the Club Penguin home page and there will be options to send them letters asking for help or what ever you need to talk to them about. Hope this helped.
If you forget your password, in Club Penguin, clicck forgot password. Then it will be sent to the email account you gave when making a penguin.