codice:
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"
"http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<script language="javascript">
function VerificaForm(FORM){
if(FORM.nominativo.value==""){
alert("Inserire nome e cognome");
FORM.nominativo.focus();
return false;
}
if(FORM.email.value==""){
alert("Inserire email");
FORM.email.focus();
return false;
}else if(!FORM.email.value.match(/^([a-zA-Z0-9_\.\-])+\@(([a-zA-Z0-9\-])+\.)+([a-zA-Z0-9]{2,4})+$/)){
alert("Email errata");
FORM.email.focus();
return false;
}
if(FORM.conoscenza.selectedIndex==0){
alert("Attenzione seleziona come sei venuto a conoscenza del sito");
FORM.conoscenza.focus();
return false;
}
if(FORM.database.selectedIndex==0){
alert("Attenzione seleziona il download");
FORM.database.focus();
return false;
}
if(!FORM.art196.checked){
alert("Attenzione seleziona l\'articolo 196/2003");
return false;
}

}
</script>
<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1">
<title>Documento senza titolo</title>
</head>

<body>
<form action="formmail.asp" method="POST" name="TheForm" id="TheForm" onSubmit="return VerificaForm(this)">
<div align="center">
<table border="0" cellspacing="0" cellpadding="5" width="374" style="border-width: 1px">
<tr>
<td><font size="1" color="#3399FF">Nome e Cognome*</font></td>
<td align="right">
<p align="center">
<font color="#3399FF">
<input type=text name="nominativo" id="nominativo" size="30" style="font-family: Verdana; font-size: 10px"></font></td>
</tr>
<tr>
<td style="border-bottom-style: none; border-bottom-width: medium">
<font size="1" color="#3399FF">Email*</font></td>
<td align="right" style="border-bottom-style: none; border-bottom-width: medium">
<p align="center">
<font color="#3399FF">
<input type=text name="email" id="email" size="30" style="font-family: Verdana; font-size: 10px"></font></td>
</tr>
<tr>
<td colspan="2" align="center" style="border-style: none; border-width: medium">


<font color="#3399FF" size="1">Conoscenza del programma*
<select size="1" name="conoscenza" id="conoscenza" style="font-family: Verdana; font-size: 10px">
  <option value="Seleziona" selected>Seleziona</option>
  <option value="Motori">Motori di ricerca</option>
  <option value="Amici">Amici</option>
  <option value="AltriSiti">Altri siti</option>
  <option value="Form">Forum</option>
</select> </font></p>


<font color="#3399FF" size="1">Richiesta download*
<select size="1" name="database" id="database" style="font-family: Verdana; font-size: 10px">
  <option value="Seleziona" selected>Seleziona</option>
  <option value="1">Database football player</option>
  <option value="2">GST Sali e Tabacchi</option>
  <option value="3">Gestione Bar</option>
  <option value="4">Gestione ristorante</option>
  <option value="5">Gestine agenti</option>
  <option value="6">Gestione agenti</option>
  <option value="7">3D Biblioteca</option>
</select></font></p>


<font size="1" color="#3399FF">Acconsento al Trattamento dei dati
personali art. 196/2003 
    <input type="checkbox" name="art196" value="si" id="art196">
</font></p>


<font color="#3399FF">
<input type="submit" value="Invia" style="font-family: Verdana; font-size: 10px">
<input type="reset" value="Cancella" style="font-family: Verdana; font-size: 10px">
</font></td>
</tr>
</table>
</div>
</form>
</body>
</html>
Cosi dovrebbe andare bene