Email sender will not send an email
after filling out the form and clicking on Send it seems that everything works as it should but email has not come after one hour
<?php
if(isset($_POST['SUBMIT'])){
$To = 'your@email.com';
$From = $_POST['Email'];
$Full_Name = $_POST['Full_Name'];
$Company = $_POST['Company'];
$Phone_Number = $_POST['Phone_Number'];
$Subject = 'Hello World';
$Message = $Full_Name . " " . $Company . " " . $Phone_Number . "Wrote the Following" . \n\n . $_POST['Message'];
$Header = "From:" . $From;
mail($To,$Subject,$Message,$Header) or die("Error!");
};
?>