App Store email address / Apple ID
The "correct" Apple ID is the one used to purchase the apps originally. 

It doesn't need to be tied to your current email address &amp; in fact doesn't actually have to be an email address at all. You can change your primary email address associated with an Apple ID...


  Change your Apple ID
  
  Follow these steps to change the email address that you use as your Apple ID.
  
  
  Sign out of every Apple service and device that uses your Apple ID.  
  Sign in to your Apple ID account page.  
  In the Account section, click Edit. Under your Apple ID, click Change Email Address.  
  Enter the email address you want to use as your Apple ID. A verification code will be sent to your new email address.  
  Enter the verification code from the email into the fields provided and start using your updated Apple ID. Didn't get the email?  
  Sign back in to all Apple services with your new Apple ID.
  
  
  You can change your Apple ID to any other email address you control,
  as long as it's not already in use as an Apple ID. If your email
  address ends with @icloud.com, @me.com, or @mac.com, you might not be
  able to change your Apple ID. You also won't see Change Email Address
  on your account page.