<?php
function spamcheck($field)
  {

  $field=filter_var($field, FILTER_SANITIZE_EMAIL);
  if(filter_var($field, FILTER_VALIDATE_EMAIL))
    {
    return TRUE;
    }
  else
    {
    return FALSE;
    }
  }
if (isset($_REQUEST['email']))
  {


  $mailcheck = spamcheck($_REQUEST['email']);
  if ($mailcheck==FALSE)
    {
    echo "Invalid input.";
    }
  else
    {
    $email = $_REQUEST['email'] ;
    $subject = $_REQUEST['subject'] ;
    $message = $_REQUEST['message'] ;
    mail("me@mysite.com", "Subject: $subject",
    $message, "From: $email" );
    echo "Thank you for your submission.";
    }
  }
?>