Hello Suresh,
    This is working as expected. Some companies do not allow their users to log into the portal so the 'email all my tickets' is available so that they can still get their tickets in a secure and easy way. 
    I do like the idea of the button automatically finding the logged in users email and pre-filling it for them as a feature though (if it doesn't already). But the ability to change the value is important. Say your a logged in user but you know you submitted another ticket with a different email address, you can simply change the email vs having to log out, navigate to the option again, and fill in the email field anytime you want a copy of tickets submitted by that second email.