Old email is locked

The Apple ID is not signed in the iPhone or device being used , it depends what correct credentials do you know for the account , knowing only correct password and Apple ID address are part of the account , the other credentials if account is set with secondary authentication like three answers for respective questions , date of birth , rescue mail address and its password are essential ( if you enter correct credentials in the link https://iforgot.apple.com/appleid#!&section=appleid a green check mark will appear account verified , sometimes the account shows zero even you contact apple support senior care advisors as its not updated on their server , the advisor will verify the account by asking few questions ( the account credentials ) when you contact them on phone Contact Apple for support and service - Apple Support

The serial number of the device , Apple ID address should be known to you , don't pretend to be another account holder , every details are in the records .

( a ) If you lose answers for Apple ID provide credit card details that was added in the account .

( b ) if you have lost Apple ID password provide invoice copy of Mac to apple support advisors .

( c ) Contact apple support , they will send a link on mail account , click on link after 24 hours to reset apple id password , however the link is valid for additional 3 hours .

( d ) Support pin is used by apple support advisors to verify the account when you know apple id password Generate a temporary Support PIN - Apple Support