PHP Contact Form won't send from mobile device

Question

I pulled this code off some site to use in various forms on my website. But I had a friend text me today saying "hey I tried to contact you through your website." Which set off an alarm in my head... "you TRIED?" So I went into heavy test mode, and it seems the only thing my forms don't get emailed to my account is when I submit them from my phone. The worst part is that the site treats the submit as if the form was sent. There is no error message. Here is the code: `

        $email_to = "info@optiprintdesign.com";
        $email_subject = "Contact Form Message - Opti Print and Design";


        function died($error) {
            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();
        }

        if(!isset($_POST['username']) ||
            !isset($_POST['usercompany']) ||
            !isset($_POST['email']) ||
            !isset($_POST['userphone']) ||
            !isset($_POST['usersite']) ||
            !isset($_POST['userlocation']) ||
            !isset($_POST['comments'])) {
            died('We are sorry, but there appears to be a problem with the form you submitted.');      
        }

        $username = $_POST['username']; 
        $usercompany = $_POST['usercompany']; 
        $email_from = $_POST['email']; 
        $userphone = $_POST['userphone']; 
        $usersite = $_POST['usersite'];    
        $userlocation = $_POST['userlocation'];         
        $comments = $_POST['comments'];

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

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

        $email_message .= "Name: ".clean_string($username)."\n";
        $email_message .= "Company: ".clean_string($usercompany)."\n";
        $email_message .= "Email: ".clean_string($email_from)."\n";
        $email_message .= "Phone: ".clean_string($userphone)."\n";
        $email_message .= "Website: ".clean_string($usersite)."\n";
        $email_message .= "Location: ".clean_string($userlocation)."\n";    
        $email_message .= "Comments: ".clean_string($comments)."\n";


    @mail($email_to, $email_subject, $email_message, $headers); 
    ?>

Answer 1

Please read up on Error Control Operators

PHP supports one error control operator: the at sign (@). When prepended to an expression in PHP, any error messages that might be generated by that expression will be ignored.