[Jinovich]

Thanks for this Marco, I have also been suggested this,

UPDATE
 user
LEFT JOIN 
user2 
ON 
    user.userid = user2.userid 
SET
    user.email = user2.email

This is obviously missing the conditionals that I would have to apply to my db as its been left so long (otherwise it will revert legit users who changed their email in the last month to their old email) but it would work for anyone else.