Zend FR

<form action="newsletter/index" method="post" id="form_newsletter" name="form_newsletter" >
    Votre email : <input type="text" id="email" name="email" value="">
    <div id="submit_search_newsletter_home">
        <a href="javascript:document.form_newsletter.submit();" class="button_jaune" onclick="">Valider</a>
    </div>
</form>

if ($this->_request->isPost()) {
$formData = $this->getRequest()->getPost();
    $email = trim($formData['email']);

    $validateurEmail = new Zend_Validate_EmailAddress();

    if ($validateurEmail->isValid($email)) {
        // inscription ok
        $pathNewsletter = $this->_realPath.'/newsletter/newsletter.csv';
        $h = fopen($pathNewsletter,"a+");

        if ($h) {
            if (is_writable($pathNewsletter)) {
                if (fwrite($h,$email.";\n") != false) {
                    $newsletterOK ="inscription ok";
                }
            }
            fclose($h);
        }
    }
    $this->view->inscription = $newsletterOK;
}