sabaraouf

$(document).ready(function() {
    $('#subscribe').submit(function() {
        if (!valid_email_address($("#email").val()))
        {
            $(".message").html('The email address you entered was invalid. Please make sure you enter a valid email address to subscribe.');
        }
        else
        {
            
            $(".message").html("<span style='color:green;'>Adding your email address...</span>");

sabaraouf

<div class="message"></div>

<form  role="form" method="post" id="subscribe">
    
    <input type="email"  id="email" name="email" placeholder="you@yourself.com" value="">
    <button type="submit">SUBSCRIBE</button>
    
</form>

sabaraouf

<?php
$api_key = "YOUR_API_KEY";
$list_id = "YOUR_LIST_ID";

require('Mailchimp.php');
$Mailchimp = new Mailchimp( $api_key );
$Mailchimp_Lists = new Mailchimp_Lists( $Mailchimp );
$subscriber = $Mailchimp_Lists->subscribe( $list_id, array( 'email' => htmlentities($_POST['email']) ) );

if ( ! empty( $subscriber['leid'] ) ) {