Sending mail with php code [error]

Hi I want to send email from my website to my email account. This is the php code:

<?php
// Check for empty fields
if(empty($_POST['name'])        ||
   empty($_POST['email'])       ||
   empty($_POST['message']) ||
   !filter_var($_POST['email'],FILTER_VALIDATE_EMAIL))
   {
    echo "No arguments Provided!";
    return false;
   }
    
$name = strip_tags(htmlspecialchars($_POST['name']));
$email_address = strip_tags(htmlspecialchars($_POST['email']));
$message = strip_tags(htmlspecialchars($_POST['message']));
    
// Create the email and send the message
$to = '***********@gmail.com'; // Add your email address inbetween the '' replacing [email protected] - This is where the form will send a message to.
$email_subject = "Interneto svetainė:  $name";
$email_body = "Jūs gavote naują pranešimą iš savo svetainės.\n\n"."Detalės:\n\nVardas: $name\n\nEl. paštas: $email_address\n\nPranešimas:\n$message";
$headers = "From: [email protected]\n"; // This is the email address the generated message will be from. We recommend using something like [email protected].
$headers .= "Atsakyti: $email_address"; 
mail($to,$email_subject,$email_body,$headers);
return true;            
?>

But I get error message from this code:

$(function() {

    $("#contactForm input,#contactForm textarea").jqBootstrapValidation({
        preventSubmit: true,
        submitError: function($form, event, errors) {
            // additional error messages or events
        },
        submitSuccess: function($form, event) {
            // Prevent spam click and default submit behaviour
            $("#btnSubmit").attr("disabled", true);
            event.preventDefault();
            
            // get values from FORM
            var name = $("input#name").val();
            var email = $("input#email").val();
            var message = $("textarea#message").val();
            var firstName = name; // For Success/Failure Message
            // Check for white space in name for Success/Fail message
            if (firstName.indexOf(' ') >= 0) {
                firstName = name.split(' ').slice(0, -1).join(' ');
            }
            $.ajax({
                url: "././mail/contact_me.php",
                type: "POST",
                data: {
                    name: name,
                    email: email,
                    message: message
                },
                cache: false,
                success: function() {
                    // Enable button & show success message
                    $("#btnSubmit").attr("disabled", false);
                    $('#success').html("<div class='alert alert-success'>");
                    $('#success > .alert-success').html("<button type='button' class='close' data-dismiss='alert' aria-hidden='true'>&times;")
                        .append("</button>");
                    $('#success > .alert-success')
                        .append("<strong>Pranešimas išsiųstas. </strong>");
                    $('#success > .alert-success')
                        .append('</div>');

                    //clear all fields
                    $('#contactForm').trigger("reset");
                },
                error: function() {
                    // Fail message
                    $('#success').html("<div class='alert alert-danger'>");
                    $('#success > .alert-danger').html("<button type='button' class='close' data-dismiss='alert' aria-hidden='true'>&times;")
                        .append("</button>");
                    $('#success > .alert-danger').append("<strong>Sorry " + firstName + ", it seems that my mail server is not responding. Please try again later!");
                    $('#success > .alert-danger').append('</div>');
                    //clear all fields
                    $('#contactForm').trigger("reset");
                },
            });
        },
        filter: function() {
            return $(this).is(":visible");
        },
    });

    $("a[data-toggle=\"tab\"]").click(function(e) {
        e.preventDefault();
        $(this).tab("show");
    });
});

// When clicking on Full hide fail/success boxes
$('#name').focus(function() {
    $('#success').html('');
});