[Plugin: Shortcode Exec PHP] can this be used to create a form handler?

Is it possible to use this to create a custom form handler in wordpress?

For example I have this code in a an Exec-PHP widget (a different plugin) that I would really love to be able to use within the shortcode php plugin (but i get a 501 error when I try)

<?php
if(!empty($_POST[‘sub_email’])) {
$email=$_POST[‘sub_email’];
$zip=$_POST[‘sub_zip’];
$Result=add_email_to_list($email, $zip, ‘listname’); }
}
if ($error != 0 || !isset($error)) { ?>
<form method=”post” name=”frmMailList” id=”frmMailList” action=”index.php”>
<table><tr><td>Email:</td><td colspan=”2″><input type=”text” name=”sub_email” id=”sub_email” style=”width:140px;” /></td></tr>
<tr><td align=”left”>Zip:</td><td align=”right”><input type=”text” name=”sub_zip” id=”sub_zip” style=”width:75px;” /></td><td><input type=”submit” value=”Sign-Up” /></td></tr></table>

</form>
<?php
}
?>
</div>

http://wordpress.org/extend/plugins/shortcode-exec-php/