I think there's a bug in forcing the user to reconfirm their email address. Line 519 of register.php.t is:
if ($FUD_OPT_2 & 1 && isset($old_email) && $old_email != $uent->email && $uent->users_opt & 1048576) {
It should be:
if ($FUD_OPT_2 & 1 && isset($old_email) && $old_email != $uent->email && !($uent->users_opt & 1048576)) {
We might as well also change the warning, so it doesn't come up for admins. This is the new line 655:
if ($uent->users_opt & 131072 && $FUD_OPT_2 & 1 && !($uent->users_opt & 1048576) ) {