Web application Deferred Sender sends post-dated email from any email client, including Gmail or Yahoo webmail accounts, helping you replace the frenzied middle-of-the-night email with a responsible first-thing-in-the-morning message. Once you've created an account, you can schedule emails by sending an email to Deferred Sender with the intended email address and future date on the first two lines of the email, followed by the email as you would normally send it. The service understands many date formats, so you can write "in 8 hours" or "tomorrow at 8pm" and the email will be sent on that date—though you can login to their panel and reschedule or delete the email if necessary. Built-in rules in Outlook offer the same functionality, but this service will work regardless of your mail client. Deferred Sender is a free service, works with any email account. Thanks, EveDarnified!