<!-- Signup Form -->
        <form id="signup-form" name="emailform" method="post" action="send_post.php">
            <input type="email" name="email" id="email" placeholder="Email Address" />
            <input type="submit" value="Sign Up" />
        </form>
<script src="assets/js/main.js"></script>

<?php
 // Fetching Values From URL
$servername = "*****";
$username = "*****";
$password = "*****";
$dbname = "email";
$email = $_POST['email'];

//Create connection
$conn = new mysqli($servername, $username, $password, $dbname);

// Check connection
if ($conn->connect_error) {
    die("Connection failed: " . $conn->connect_error);
}

//Insert the data

mysqli_query($conn,"INSERT INTO email (email)
VALUES ('$email')");


$conn->close();
?>

//Submitting the form
                            $('#signup-form').submit(function () {

                                $.ajax({
                                    type: "POST",
                                    url: "send_post.php",
                                    data: $("#signup-form"),
                                    success: function () {
                                        alert("success");
                                    }
                                });
                                e.preventDefault();
                                return false;
                            });