If you look into
register.php
you will find this one:
if (!eregi("^[_\.0-9a-z\-]+@([0-9a-z][0-9a-z-]+\.)+[a-z]{2,6}$", $email)) $error .= '<li>' . $lang_register_php['err_invalid_email'];
If you look into
profile.php
you will not find any check for email format.
So users can enter any email they want like: testest.com or test@test