mailer.php

<?php

  if ($_SERVER["REQUEST_METHOD"] == "POST") {
    $name = strip_tags(trim($_POST["name"]));
      $name = str_replace(array("\r", "\n"),array("", ""),$name);
    $email = filter_var(trim($_POST["email"]), FILTER_SANITIZE_EMAIL);
    $message = trim($_POST["message"]);

    if ( empty($name) OR empty($message) OR !filter_var($email, FILTER_VALIDATE_EMAIL)) {
      http_response_code(400);
      echo "There was an error with your submission. Please complete the form and try again.";
      exit;
    }

    $recipient = "Insert email here";

    $subject = "New contact from $name";

    $email_content = "Name: $name\n";
    $email_content .= "Email: $email\n\n";
    $email_content .= "Message: \n$message\n";

    $email_headers = "From: $name <$email>";

    if (mail($recipient,$subject,$email_content,$email_headers)) {
      http_response_code(200);
      echo "Thank you! Your message has been sent.";
    } else {
      http_response_code(500);
      echo "Something went wrong and we couldn't send your message.";
    }
  }

  else {
    http_response_code(403);
    echo "There was a problem with your submission, please try again.";
  }

?>