New comment email notification and 'insert_comment_insert_array' hook

I hame some input fields on my comment form, that I show for non-registered members. They are: ‘name’, ‘email’ and ‘comment text’.

And my task was to add string “Guest” to text user typed in the field ‘name’. So I created extension where I use ‘insert_comment_insert_array’ hook:

public function concat_username($data)
{
    if($data['author_id'] != 0)
        return $data;

    $data['name'] = "Guest ".$data['name'];

    return $data;
}

And it works. But new comment email notifications that I receive after new comment was posted contain user name without my string “Guest”.

May be anyone knows what’s wrong?