Also, the Out of Office Rule will never reply to yourself. So you can't send yourself an e-mail message from the same mailbox and expect a reply to that same mailbox -- those kind of looping replies are considered bad form.
If you want to test someone else's Out of Office reply, just send them an e-mail message from your mailbox (as long as you don't have their mailbox in your E-mail panel). To test your own Out of Office reply, you would need to send an e-mail to yourself from a different e-mail address.