Good question. The people who can help update your Apple ID to an accessible email address are atexpresslane.apple.com
After you've navigated there...
- Choose iTunes
- Choose iTunes Store
- Choose Purchases, Billing, ...
- Choose topic not listed
- In the box that appears type "no longer have access to my Apple ID email address and I need to reset my password. do not know security questions" (this will allow you to schedule a call to resolve the issue)
- Click Continue
- Click "Schedule a Call"
Someone will contact you to resolve this issue.
In the future, you might using only email addresses that you can access permanently.