<<il nome della casella indicato in MAILFROM non è valido>>

questo mi restituisce la pagina dopo che cliko su invia:

CHe è anche se è un campo Hidden, come faccio a mettere il mittente se varia a seconda di chi scrive la mail?

Posto il codice della pagina per intero.

<form action="http://xxxx.xxxxx.it/servizi/FromMail/formmail.asp" method=post>
<input type=hidden name=mailto value="info@xxxxxxxxxxxxx.it">

<th width="142" align="left" class="Stile11" scope="col">Nome</th>
<th width="313" colspan="2" scope="col">

<div align="left">
<input name="textfield" type="text" size="25" maxlength="50">
</div>
<tr>
<th align="left" class="Stile11" scope="col">Cognome</th>
<th colspan="2" scope="col"><div align="left">
<input name="textfield" type="text" size="25" maxlength="50">

</div></th>
</tr>
<tr>
<th align="left" class="Stile11" scope="col">Ragione Sociale</th>
<th colspan="2" scope="col"><div align="left">

<input name="textfield" type="text" size="25" maxlength="50">

</div></th>
</tr>
<tr>
<th align="left" class="Stile11" scope="col">Indirizzo</th>
<th colspan="2" scope="col"><div align="left">

<input name="textfield" type="text" size="40" maxlength="50">

</div></th>
</tr>
<tr>
<th align="left" class="Stile11" scope="col">Citta'</th>
<th colspan="2" scope="col"><div align="left">

<input name="textfield" type="text" size="25" maxlength="50">

</div></th>
</tr>
<tr>
<th align="left" class="Stile11" scope="col">Provincia (solo Italia) </th>
<th colspan="2" scope="col"><div align="left">

<select name="select">
<option>AG</option>
<option>AL</option>
<option>AN</option>
<option>AO</option>
<option>AQ</option>
<option>AR</option>
<option>AP</option>
<option>AT</option>
<option>AV</option>
<option>BA</option>
<option>BL</option>
<option>BN</option>
<option>BG</option>
<option>BI</option>
<option>BO</option>
<option>BZ</option>
<option>BS</option>
<option>BR</option>
<option>CA</option>
<option>CL</option>
<option>CB</option>
<option>CE</option>
<option>CT</option>
<option>CZ</option>
<option>CH</option>
<option>CO</option>
<option>CS</option>
<option>CR</option>
<option>KR</option>
<option>CN</option>
<option>EN</option>
<option>FE</option>
<option>FI</option>
<option>FG</option>
<option>FC</option>
<option>FR</option>
<option>GE</option>
<option>GO</option>
<option>GR</option>
<option>IM</option>
<option>IS</option>
<option>SP</option>
<option>LT</option>
<option>LE</option>
<option>LC</option>
<option>LI</option>
<option>LO</option>
<option>LU</option>
<option>MC</option>
<option>MN</option>
<option>MS</option>
<option>MT</option>
<option>ME</option>
<option>MI</option>
<option>MO</option>
<option>NA</option>
<option>NO</option>
<option>NU</option>
<option>OR</option>
<option>PD</option>
<option>PA</option>
<option>PR</option>
<option>PV</option>
<option>PG</option>
<option>PU</option>
<option>PE</option>
<option>PC</option>
<option>PI</option>
<option>PT</option>
<option>PN</option>
<option>PZ</option>
<option>PO</option>
<option>RG</option>
<option>RA</option>
<option>RC</option>
<option>RE</option>
<option>RI</option>
<option>RN</option>
<option>Roma</option>
<option>RO</option>
<option>SA</option>
<option>SS</option>
<option>SV</option>
<option>SI</option>
<option>SR</option>
<option>SO</option>
<option>TA</option>
<option>TE</option>
<option>TR</option>
<option>TO</option>
<option>TP</option>
<option>TN</option>
<option>TV</option>
<option>TS</option>
<option>UD</option>
<option>VA</option>
<option>VE</option>
<option>VB</option>
<option>VC</option>
<option>VR</option>
<option>VV</option>
<option>VI</option>
<option>VT</option>
</select>

</div></th>
</tr>
<tr>
<th align="left" class="Stile11" scope="col">C.A.P.</th>
<th colspan="2" scope="col"><div align="left">

<input name="textfield" type="text" size="6" maxlength="6">

</div></th>
</tr>
<tr>
<th align="left" class="Stile11" scope="col">Telefono fisso </th>
<th colspan="2" scope="col"><div align="left">

<input name="textfield" type="text" size="12" maxlength="10">

</div></th>
</tr>
<tr>
<th align="left" class="Stile11" scope="col">Telefono cellulare </th>
<th colspan="2" scope="col"><div align="left">

<input name="textfield" type="text" size="12" maxlength="10">

</div></th>
</tr>
<tr>
<th align="left" class="Stile11" scope="col">Fax</th>
<th colspan="2" scope="col"><div align="left">

<input name="textfield" type="text" size="12" maxlength="10">

</div></th>
</tr>
<tr>
<th align="left" class="Stile11" scope="col">E-mail</th>
<th colspan="2" scope="col"><div align="left">

<input name="textfield" type="text" size="25" maxlength="50">

</div></th>
</tr>
<tr>
<th align="left" class="Stile11" scope="col">Oggetto richiesta </th>
<th colspan="2" scope="col"><div align="left">

<input name="textfield" type="text" size="25" maxlength="50">

</div></th>
</tr>
<tr>
<th align="left" class="Stile11" scope="col">Testo richiesta </th>
<th colspan="2" scope="col"><div align="left">

<textarea name="textarea" cols="35" rows="6"></textarea>

</div></th>
</tr>
<tr>
<th align="left" class="Stile11" scope="col"></th>
<th scope="col"><div align="left">

<input type="submit" name="Submit" value="Invia">

</div></th>
<th scope="col"><div align="left">
</form>