Have you ever said you would send an email with an attachment, and forget to attach it? Go to Delay Sending Email.
You can also delay your mail message for several days, and deliver it at a specific time of day. To hold off a message, use Outlook and prepare your message in the usual way, but before you click "Send", click on "Options." The Message Options box opens, under the Delivery Options, click in the box that says "Do not deliver before:, enter a date and time here, then close the box. Now hit the "Send" button.
This is a good way to freak out your friends. When you go on vacation, set up several email messages and have them delivered while you are away.