FREE Email Form - PHP

Hi guys,

I’ve only been practicing PHP for a week now but I was searching for email forms that I can use for my personal website and found this one. The thing I like about this code is it’s VALIDATION. But I think something is weird in a lot of way because the original code would say that the NAME, LASTNAME, EMAIL are INVALID even if I entered a correct one. Can someone explain to me why this is happening?

<?php
if(isset($_POST[‘email’])) {

// EDIT THE 2 LINES BELOW AS REQUIRED
$email_to = "[email protected]";
$email_subject = "Your email subject line";
 
 
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.&lt;br /&gt;&lt;br /&gt;";
    echo $error."&lt;br /&gt;&lt;br /&gt;";
    echo "Please go back and fix these errors.&lt;br /&gt;&lt;br /&gt;";
    die();
}
 
// validation expected data exists
if(!isset($_POST['first_name']) ||
    !isset($_POST['last_name']) ||
    !isset($_POST['email']) ||
    !isset($_POST['telephone']) ||
    !isset($_POST['comments'])) {
    died('We are sorry, but there appears to be a problem with the form you submitted.');       
}
 
$first_name = $_POST['first_name']; // required
$last_name = $_POST['last_name']; // required
$email_from = $_POST['email']; // required
$telephone = $_POST['telephone']; // not required
$comments = $_POST['comments']; // required
 
$error_message = "";
$email_exp = "/^[A-Z0-9._%-]+@[A-Z0-9.-]+\.[A-Z]{2,4}$/";

if(!preg_match($email_exp,$email_from)) {
$error_message .= ‘The Email Address you entered does not appear to be valid.<br />’;
}
$string_exp = “/^[a-z .’-]+$/”;
if(!preg_match($string_exp,$first_name)) {
$error_message .= ‘The First Name you entered does not appear to be valid.<br />’;
}
if(!preg_match($string_exp,$last_name)) {
$error_message .= ‘The Last Name you entered does not appear to be valid.<br />’;
}
if(strlen($comments) < 2) {
$error_message .= ‘The Comments you entered do not appear to be valid.<br />’;
}
if(strlen($error_message) > 0) {
died($error_message);
}
$email_message = "Form details below.

";

function clean_string($string) {
  $bad = array("content-type","bcc:","to:","cc:","href");
  return str_replace($bad,"",$string);
}
 
$email_message .= "First Name: ".clean_string($first_name)."

";
$email_message .= "Last Name: “.clean_string($last_name).”
";
$email_message .= "Email: “.clean_string($email_from).”
";
$email_message .= "Telephone: “.clean_string($telephone).”
";
$email_message .= "Comments: “.clean_string($comments).”
";

// create email headers
$headers = 'From: '.$email_from."
“.
'Reply-To: '.$email_from.”
" .
‘X-Mailer: PHP/’ . phpversion();
@mail($email_to, $email_subject, $email_message, $headers);
?>

<!-- include your own success html here -->

Thank you for contacting us. We will be in touch with you very soon.

<?php
}
?>