On a successful submission the form is hidden and a “thank you” message is shown in its place.

<aside class="mzp-c-newsletter">
    <div class="mzp-c-newsletter-image">
        <img src="../../img/newsletter-image.png" width="346" height="346" alt="">
    </div>

    <form id="newsletter-form" class="mzp-c-newsletter-form hidden" action="https://basket.mozilla.org/news/subscribe/" method="post">
        <!-- The value for the source_url field below should match the URL of your page where the newsletter form appears-->
        <input type="hidden" name="source_url" value="https://www.mozilla.org/">

        <header class="mzp-c-newsletter-header">
            <h3 class="mzp-c-newsletter-title">Love the Web?</h3>
            <p class="mzp-c-newsletter-tagline">Get the Mozilla newsletter and help us keep it open and free.</p>
        </header>

        <fieldset class="mzp-c-newsletter-content">
            <div class="mzp-c-form-errors" id="newsletter-errors">
                <ul class="mzp-u-list-styled">
                    <li class="error-email-invalid">
                        Please enter a valid email address
                    </li>
                    <li class="error-privacy-policy">
                        You must agree to the privacy notice
                    </li>
                </ul>
            </div>

            <label for="id_email">Your email address:</label>
            <input type="email" id="id_email" name="email" required="" maxlength="320" placeholder="yourname@example.com" class="mzp-js-email-field">

            <div id="newsletter-details" class="mzp-c-newsletter-details">

                <label for="id_country">Country</label>
                <select name="country" id="id_country">
                    <option value="us">United States</option>
                    <option value="de">Germany</option>
                    <option value="fr">France</option>
                    <option value="in">India</option>
                    <option value="jp">Japan</option>
                    <option value="es">Spain</option>
                </select>

                <label for="id_lang">Language</label>
                <select name="language" id="id_lang">
                    <option value="en">English</option>
                    <option value="de">Deutsch</option>
                    <option value="es">Español</option>
                    <option value="fr">Français</option>
                    <option value="hi-IN">हिन्दी (भारत)</option>
                    <option value="ja">日本語</option>
                </select>

                <fieldset class="mzp-u-inline">
                    <legend>I want information about:</legend>
                    <p>
                        <label for="id_newsletters_0" class="mzp-u-inline">
                            <input type="checkbox" name="newsletters" value="mozilla-foundation" id="id_newsletters_0" checked> Mozilla Foundation
                        </label>

                        <label for="id_newsletters_1" class="mzp-u-inline">
                            <input type="checkbox" name="newsletters" value="mozilla-and-you" id="id_newsletters_1" checked> Firefox
                        </label>
                    </p>
                </fieldset>

                <fieldset class="mzp-u-inline">
                    <legend>Format</legend>
                    <p>
                        <label for="format-html" class="mzp-u-inline">
                            <input type="radio" id="format-html" name="format" value="H" checked> HTML
                        </label>
                        <label for="format-text" class="mzp-u-inline">
                            <input type="radio" id="format-text" name="format" value="T"> Text
                        </label>
                    </p>
                </fieldset>

                <p>
                    <label for="privacy" class="mzp-u-inline">
                        <input type="checkbox" id="privacy" name="privacy" required aria-required="true">
                        I’m okay with Mozilla handling my info as explained in <a href="https://www.mozilla.org/privacy/websites/">this Privacy Notice</a>
                    </label>
                </p>
            </div>

            <p class="mzp-c-form-submit">
                <button type="submit" class="mzp-c-button" id="newsletter-submit">Sign up now</button>
                <span class="mzp-c-fieldnote">We will only send you Mozilla-related information.</span>
            </p>
        </fieldset>
    </form>

    <div id="newsletter-thanks" class="mzp-c-newsletter-thanks">
        <h3>Thanks!</h3>
        <p>If you haven’t previously confirmed a subscription to a Mozilla-related newsletter you may have to do so. Please check your inbox or your spam filter for an email from us.</p>
    </div>

</aside>