type of emails from Contacts.app in AppleScript (on El Capitan)
allEmails is a list that contains several lists, each sublist contains emails of a contact.

email is an object, you need to get the value of this object.

So, you need a loop for each list, and another loop for each value.

tell application "Contacts"
    set myList to value of emails of people
end tell
repeat with aList in myList
    repeat with anEmail in aList
        display dialog anEmail
    end repeat
end repeat