为什么我的 php 电子邮件脚本向我的垃圾邮件发送电子邮件不在我的收件箱中

这是我下面的php代码。当我单击"发送电子邮件"按钮时，它工作正常。但它没有出现在我的收件箱中。它被路由到垃圾邮件文件夹：

<?php 
  function sendmail(){
        $message = $_POST['message'];
        $email = $_POST['email'];
        $name  = $_POST['name'];
        $lastname  = $_POST['lastname'];
        $to = 'mpylla@gmail.com';
        $subject = 'From :'.$email;
        $message1 = 'From: '.$name."'nEmail: ".$email."'nMessage: ".$message;
        mail($to, $subject, $message1);
        }

        sendmail();
?>

这个 ajax 脚本在我的 HTML 代码中：

$("#submit").click(function(e) {
    var name = $("#name").val();
    var lastname = $("#lastname").val();
    var email = $("#email").val();
    var message = $("#message").text();
    var emailReg = /^(['w-'.]+@(['w-]+'.)+['w-]{2,4})?$/;
    if (!emailReg.test(email)) {
        alert('Ju lutem shkruan nje e-mail valide');
        return false;
    }
    if (email.length == 0) {
        alert("Email duhet te shenohet");
        return false;
    }
    if (name.length == 0) {
        alert("Emri duhet te shenohet");
        return false;
    }
    if (lastname.length == 0) {
        alert("Mbiemri duhet te shenohet");
        return false;
    }
    if (message.length == 5) {
        alert("Mesazhi duhet te shenohet");
        return false;
    } else {
        $.ajax({
            type: "POST",
            url: "mail.php",
            data: $("#myform").serialize(),
            success: function(response) {
                $("#sukses").fadeIn('slow');
                setTimeout(function() {
                    $("#sukses").fadeOut('slow');
                    document.getElementById('myform').reset();
                }, 100);
                clearInterval();

            }
        });
    }


    e.preventDefault();
    e.stopPropagation();
});