"Permanent" means just that. If you're using Exchange, examine the "Recover
Deleted Items" feature (although a permanent deletion may circumvent that
feature). If a PST, your best bet is to recover it from the most recent
backup you've made. You DO make frequent backups, correct? If not, you
only hope is this: http://www.howto-outlook.com/howto/restoredeleteditemsfromanoutlookpst.htm