$localonly = $row['localonly'];
:
if ($newlocalonly=="localonly") {
    $query = "UPDATE virtual,accountuser SET localonly='localonly', alias='$newalias@$domain', dest='$dest' WHERE alias='$alias' and accountuser.username=virtual.username";
} else {
     $query = "UPDATE virtual,accountuser SET localonly='OK', alias='$newalias@$domain', dest='$dest' WHERE alias='$alias' and accountuser.username=virtual.username";
}
} else {
     if ($newlocalonly=="localonly") {
         $query = "UPDATE virtual,accountuser SET localonly='localonly', alias='$newalias', dest='$dest' WHERE alias='$alias' and accountuser.username=virtual.username";
} else {
$query = "UPDATE virtual,accountuser SET localonly='OK', alias='$newalias', dest='$dest' WHERE alias='$alias' and accountuser.username=virtual.username";
}
:
<td>
   <input class="inputfield"
    type="checkbox"
    name="newlocalonly" value="localonly"
<?php
    if ($localonly!="OK") {
         echo "checked";
   }
										         ?>
</td>