Quisera saber que estoy haciendo mal?

[Bvegac]

Quisiera saber que estoy haciendo mal para que se envie el formulario aun estando vacio, les paso la programacion que tengo.

HTML

<div>
<form enctype="multipart/form-data" action="../procesar.php" method="POST" id="form-136237216953296517">
<div id="136237216953296517-form-parent" class="wsite-form-container" style="margin-top:10px;">
<ul class="formlist" id="136237216953296517-form-list">
<h2 class="wsite-content-title" style="text-align:left;"><font color="#00adff"><span style="line-height: 0; display: none;"></span>Cont&aacute;ctanos.<span style="line-height: 0; display: none;"></span></font></h2>

<div><div class="wsite-form-field" style="margin:5px 0px 5px 0px;">
<label class="wsite-form-label" for="input-936381694598310108">Nombre <span class="form-required">*</span></label>
<div class="wsite-form-input-container">
<input id="input-936381694598310108" class="wsite-form-input wsite-input wsite-input-width-370px" type="text" name="Nombre" placeholder="Escribe aquí tu nombre" required/>
</div>
<div id="instructions-936381694598310108" class="wsite-form-instructions" style="display:none;"></div>
</div></div>

<div><div class="wsite-form-field" style="margin:5px 0px 5px 0px;">
<label class="wsite-form-label" for="input-936381694598310108">Apellido <span class="form-required">*</span></label>
<div class="wsite-form-input-container">
<input id="input-936381694598310108" class="wsite-form-input wsite-input wsite-input-width-370px" type="text" name="Apellido" placeholder="Escribe aquí tu apellido" required/>
</div>
<div id="instructions-936381694598310108" class="wsite-form-instructions" style="display:none;"></div>
</div></div>

<div><div class="wsite-form-field" style="margin:5px 0px 5px 0px;">
<label class="wsite-form-label" for="input-936381694598310108">Correo electrónico <span class="form-required">*</span></label>
<div class="wsite-form-input-container">
<input id="input-936381694598310108" class="wsite-form-input wsite-input wsite-input-width-370px" type="email" name="E-mail" placeholder="Escribe aquí tu E-mail" required />
</div>
<div id="instructions-936381694598310108" class="wsite-form-instructions" style="display:none;"></div>
</div></div>

<div><div class="wsite-form-field" style="margin:5px 0px 5px 0px;">
<label class="wsite-form-label" for="input-823567093955212889">Número Teléfonico <span class="form-required">*</span></label>
<div class="wsite-form-input-container">
<input id="input-823567093955212889" class="wsite-form-input wsite-input wsite-input-width-370px" type="text" name="Telefono" placeholder="Escribe aquí tu número teléfonico" required />
</div>
<div id="instructions-823567093955212889" class="wsite-form-instructions" style="display:none;"></div>
</div></div>

<div><div class="wsite-form-field" style="margin:5px 0px 5px 0px;">
<label class="wsite-form-label" for="input-177776419854873638">Comentario <span class="form-required">*</span></label>
<div class="wsite-form-input-container">
<textarea id="input-177776419854873638" class="wsite-form-input wsite-input wsite-input-width-370px" name="Comentario" style="height: 200px"></textarea>
</div>
<div id="instructions-177776419854873638" class="wsite-form-instructions" style="display:none;"></div>
</div></div>
</ul>
</div>
<div style="display:none; visibility:hidden;">
<input type="text" name="wsite_subject" />
</div>
<div style="text-align:left; margin-top:10px; margin-bottom:10px;">
<input type="hidden" name="form_version" value="2" />
<input type="hidden" name="wsite_approved" id="wsite-approved" value="approved" />
<input type="hidden" name="ucfid" value="136237216953296517" />
<input type='submit' style='position:absolute;top:0;left:-9999px;width:1px;height:1px' /><a class='wsite-button' onclick="document.getElementById('form-136237216953296517').submit()"><span class='wsite-button-inner'>Enviar</span></a>
</div>
</form>

PHP

<?php
$nombre = $_POST['Nombre'];
$apellido = $_POST['Apellido'];
$email = $_POST['E-mail'];
$telefono = $_POST['Telefono'];
$comentario = $_POST['Comentario'];

// comienzo de estructura de envio

$mailsend = mail ( '[email protected]' , 'Mensaje de Innova Digital', "Nombre: $nombre\r\nApellido: $apellido\r\nE-mail: $email\r\nTelefono: $telefono\r\nComentario: $comentario\r\n");


if ($mailsend) {
echo '<script>alert("Tu mensaje ha sido enviado con éxito. Muchas gracias"); location.href= "index.html"</script>';
}


?>