<FORM NAME = "mail_form" ACTION = "mailto:Has-admin@mail.ru?Subject=Send from Mail Form" METHOD = "POST" ENCTYPE = "text/plain">
<INPUT TYPE = "hidden" SIZE = 0 NAME = "Host" value="<!--#echo var="REMOTE_HOST"-->">
<INPUT TYPE = "hidden" SIZE = 0 NAME = "IP" value="<!--#echo var="REMOTE_ADDR"-->">
<table>
<tr>
<td>
Имя:
<td>
<INPUT TYPE = "text" NAME = "Name" size="30">
<TR>
<td>
Тема:
<td>
<INPUT TYPE = "text" NAME = "Subject" size="30">
<tr>
<td>
Город:
<td>
<INPUT TYPE = "text" NAME = "City" size="30">
<tR>
<td>
Ваш сайт:
<td>
<INPUT TYPE = "text" NAME = "Site" size="30" value="http://">
<tr>
<td>
Сообщение:
<td>
<TEXTAREA NAME="Comments" COLS=50 ROWS=6>
</TEXTAREA>
</table>
<CENTER>
<INPUT TYPE = "submit" VALUE = "Отправить">
<INPUT TYPE = "button" VALUE = "Вернуться" onClick="history.back();">
</CENTER>
</FORM>

 Обратите внимание на 2 скрытых поля:
<INPUT TYPE = "hidden" SIZE = 0 NAME = "Host" value="<!--#echo var="REMOTE_HOST"-->">
<INPUT TYPE = "hidden" SIZE = 0 NAME = "IP" value="<!--#echo var="REMOTE_ADDR"-->">
 Они определяют и отправляют IP адрес и Remote Host.