var date = new Date();
var hours = date.getHours();
var minute = date.getMinutes();
if (hours === 15 && minute => 31){
alert("открыто");
}
if (hours === 15 && minute === 33){
alert("Закрыто");
}
<?php
$name = trim($_POST['name']);
$email = trim($_POST['email']);
$messege = trim($_POST['messege']);
$to = "почта";
$from = "test@rush.ru";
$subject = "Сообщение с сайта";
$headers = "From: $from\r\nReply-To: $from\r\nContent-type: text/plain; charset=utf-8\r\n";
mail($to, $subject, $messege, $headers);
?>