This account guard thing is terrible.
I'm testing it with my wife on a different computer and it asks for the code when signing into the actual game but requires no code at all to sign into the website. Meaning it's completely useless. If they had your password, signed into the website, not receiving a code authorization, then change the email, then signed into the game, it would send the code to the hacker's email and effectively render the account guard useless.
Not to mention attempting to go into the account guard management page prompts me for a code literally every single time I try. Even reloading the tab asks for a new code.
Broken. Not sure how anyone is expected to rely on this thing for security.
I just logged into my wifes account, changed the email to mine, it sent the confirmation to MY email that I was changing it to, and I changed her email. It did nothing but tell her I was doing it, didn't ask for any confirmation. She couldn't stop it if she tried and account guard did nothing.