Soda stream form submit event + cookie saving.

<script>
    (function() {
        var cookieEmailName = '__subscribedus';
        var form = document.querySelector('.' + self.identifier + ' [tabindex] form');
        form.setAttribute('bi-type', 'adoric-form');
        form.setAttribute('bi-id', self.campaignTitle);

        function writeCookie(key, value, expires) {
            var now = new Date();
            var time = now.getTime();
            time += 3600 * 1000 * 12;
            now.setTime(time);
            var cookieString = key + '=' + value + '; expires=' + now.toUTCString() + '; path=/';
            if (expires) {
                cookieString += cookieString + '; expires=' + now.toUTCString() + '; path=/';
            } else {
                cookieString += cookieString + '; expires=Fri, 31 Dec 9999 23:59:59 GMT"; path=/';
            }
            window.document.cookie = cookieString;
            return value;
        };

        function utf8_to_b64(str) {
            return window.btoa(unescape(encodeURIComponent(str)));
        }
        form.addEventListener('submit', function() {
            var emailField = form.querySelector('INPUT[name*="mail"]');
            if (emailField) {
                writeCookie(cookieEmailName, utf8_to_b64(emailField.value));
            }
        });
    })();
</script>