电子邮件发件人将不会发送电子邮件

Question

电子邮件发件人不会发送电子邮件

填写表格并单击“发送”后，似乎一切正常，但一小时后仍未收到电子邮件

<?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!");

  };

?>