Runescape Email login / help

hey guys my most recent account was shared with a m8 but hes given it to me recently , however i think hes trying to hack it back.

the login is his email adress, however am i correct in thinking if i change the email adress to my own even though it wont change the username email ( which is his ) he then wont be able to recover it via his email as my email will be linked to the account ?