Email form getting error when submitting

PHP
1

I know this is a simple thing I am overlooking but I cannot seem to find it.

When I test my form I am getting this error

We are very sorry, but there were error(s) found with the form you submitted. These errors appear below.

The Message you entered does not appear to be valid.


Please go back and fix these errors.

Here is the form code

<?php
    if(isset($_POST['email'])) {

    // EDIT THE 2 LINES BELOW AS REQUIRED
    $email_to = "myemail@gmail.com";
    $email_subject = "Submission Form";

    function died($error) {
        // your error code can go here
        echo "We are very sorry, but there were error(s) found with the form you
       submitted. ";
        echo "These errors appear below.<br /><br />";
        echo $error."<br /><br />";
        echo "Please go back and fix these errors.<br /><br />";
        die();
    }

   // validation expected data exists
    if(!isset($_POST['name']) ||
        !isset($_POST['email']) ||
        !isset($_POST['subject']) ||
        !isset($_POST['message'])) {
        died('We are sorry, but there appears to be a problem with the form you
    submitted.');
    }

    $name = $_POST['name']; // required
    $email = $_POST['email']; // required
    $subject = $_POST['subject']; // required
    $message = $_POST['message']; // required

    $error_message = "";
    $string_exp = "/^[A-Za-z0-9 .'-]+$/";
	
  if(!preg_match($string_exp,$name)) {
    $error_message .= 'The Name you entered does not appear to be valid.<br />';
  }
    $email_exp = '/^[A-Za-z0-9._%-]+@[A-Za-z0-9.-]+\\.[A-Za-z]{2,4}$/';
  if(!preg_match($email_exp,$email)) {
    $error_message .= 'The Email Address you entered does not appear to be valid.<br />';
  }
  if(!preg_match($string_exp,$subject)) {
    $error_message .= 'The Subject you entered does not appear to be valid.<br />';
  }
  if(!preg_match($string_exp,$message)) {
    $error_message .= 'The Message you entered does not appear to be valid.<br />';
  }
  if(strlen($error_message) > 0) {
    died($error_message);
  }


    $email_message .= "Name: ".clean_string($name)."\
";
    $email_message .= "Email: ".clean_string($email)."\
";
    $email_message .= "Subject: ".clean_string($subject)."\
";
    $email_message .= "Message: ".clean_string($message)."\
";


// create email headers
$headers = 'From: '.$email_from."\\r\
".
'Reply-To: '.$email_from."\\r\
" .
'X-Mailer: PHP/' . phpversion();
@mail($email_to, $email_subject, $email_message, $headers);
header('Location: thank-you.html');

}
?>

Like I said, I know I am looking over something.

2

Well, for that error, here what’s tripping it:


$string_exp = "/^[A-Za-z0-9 .'-]+$/";
if(!preg_match($string_exp,$message)) {
    $error_message .= 'The Message you entered does not appear to be valid.<br />';
  }

I’m not that great with regex, but why even run it? This looks like a hard way to remove some sort of injection, but there are other ways.