PHP Email Error; Works on a laptop browser, not on mobile browser [duplicate]

My website uses a normal html form and php code to send an email. The email function works perfectly fine when I try it using a laptop browser. However, if I attempt to do the same from my mobile's browser, no mail is being sent. Could someone give me a reason for this and/or help me fix the problem?

Here's the code:-

<?php 

        if(isset($_POST['submit']))
        {
            $to = "sample@email.com"; // this is receiver's Email address
            $from = $_POST['email']; // this is the sender's Email address
            $name = $_POST['name'];
            $subject = "Contact Form submission";
            $message = "Name:".$name . "\n" . "Email:" .$from. "\n" . "Message: " . $_POST['message'];


            $headers = "From:" . $from;

            mail($to,$subject,$message,$headers);

            $alert_message =  "Mail Sent. Thank you " . $name . ", we will contact you shortly.";

            echo "<script type='text/javascript'>alert('$alert_message');</script>";

        }
    ?>