In the Form Builder go to the Setting, then Comfirm Page. There select Redirect to another URL.
Enter the url for your custom php script.
Here's a quick dirty example to get you started. Save this as a php page and upload it to your host. Enter it's location in your Form Builder option Redirect to another URL.
<?php
session_start(); ?>
<html lang="en">
<head>
<meta charset="utf-8">
<title></title>
</head>
<body>
<?php
$post = $_SESSION['post']; // This is getting the post array
$email = $post['email']; // *******This is getting my email input name from the array called "email"
// Add more as needed for each input on your form. Adjust to your input name.
if(isset($email)) {echo'You made it to my page.<br><br> Here is what you chose on my form.<br><br>
The email you entered was '.$email.'<br><br>
Refresh your browser to see the Session unset.<br><br>
Here\'s the session array. The one that holds the form variables is named post.';
echo '<pre>' . print_r($_SESSION, TRUE) . '</pre>';
//Email information
$to = "myname@mydomain.com"; // *******Edit to where you want the email to go. Can be multiple.
$email = $email;
$subject = 'Your Form';
$message = 'This message has a custom from email of '.$email;
//Send email
mail($to, $subject, $message, "From:" . $email);
//Email response
echo "Thank you for contacting us!";
}
else{
echo 'You should check out my <a href="email-from/index.html">email form.</a>'; //******* Edit to your form location
}
unset($_SESSION['post']); // This unsets the $_SESSION['post'] array
// Here's how to unset one variable.
//$key=array_search($post['email'],$_SESSION['post']);
// if($key!==false) unset($_SESSION['post'][$key]);
?>
</body>
</html>