Remove unread PMs older than a year, and remove all PMs older than 5 years **THIS IS UNTESTED**

pm.php

<?php
// drop this in your root e107 directory
include("class2.php");

// unread in the last 12 months
$sql->db_Delete("private_msg", "pm_sent < ".(time() - 31556926)." AND pm_read = 0") or die(mysql_error());

// older than 5 years
$sql->db_Delete("private_msg", "pm_sent < ".(time() - 157784630)) or die(mysql_error());

?>