Remove all characters except letters, digits and !#$%&'*+-=?^_`{|}~@.[].
var_dump(filter_var('
[email protected]', FILTER_SANITIZE_EMAIL));
var_dump(filter_var("!#$%&'*+-=?^_`{|}~.[]@example.com", FILTER_SANITIZE_EMAIL));
var_dump(filter_var('john/@example.com', FILTER_SANITIZE_EM...