Legally there is nothing wrong with this move, although it does raise some issues about account security if the email address you use to login would be widely known.
If you are worried about that, the easiest thing would be to simply not use the RealID option, and continue playing as you do now.
Blizzard does not have an email address to use, but they do have support on their website. Links to their Help Page and a page to open a ticket for a specific game are in the Related Links.
how do you know your friends email address?
We do not require a friend's email address. We use your email address for you to get notifications of an answer to a question you asked.
Contact a friend to whom you sent email from that address. Ask him what the address was.
To exchange an email archive with a friend, all you need to do is forward the email. You can forward the email to your friend by pressing the forward button, and entering your friend's email address.
If you sync your friends email address on your device you will receive their mail.
Ask her.
Unless you happen to be a friend that knows his private email address, no.
In your address book
Type your answer here... Do you want to be my friend
gabi navon
You Friend Request them or ask them to exchange email addresses with you.By info section IF they have it for display.