Contact form keeps sending blank emails

Question

Here's my contact form php code. Every morning I receive a blank response from my contact form.

<?php 
     $to = "test@youremail.com";
     $subject = "Contact Form Inquiry"; 
     $name = $_POST['name'] ; 
     $email = $_POST['email'] ; 
     $message = $_POST['message'] ; 
     $content = "From: $name \n Message: $message";
     $headers = "From: $email "; 
     $sent = mail($to, $subject, $content, $headers) ; 
     if($sent) 
     {
        print "Your mail was sent successfully"; 
     }
     else 
     {
        print "We encountered an error sending your mail"; 
     }
 ?> 

Why do I receive this response?

Answer 1

$_POST['message'] ;

Please check if this variable coming up with any value from your form.

Answer 2

Use a CAPTCHA or similar alternatives, there are a lot of bots out there. You could also generate a CSRF token (look at the Wikipedia article if you aren't sure about it), so the form will require it before actually sending the e-mail. Many frameworks do this for you.