When you are out of the office and want to let people who email you that you will not be getting to their email anytime soon it is nice to send an auto-reply such as:
"I'm out of the office today."

This way your correspondents will know about your unavailability.

Setting this up requires that you have your computer on when you are out and your email client open. The steps to set this up depend on your email client. See below for instructions for specific clients.

Microsoft Office Outlook 2007

Microsoft Outlook Express has no support for this functionality.

Apple Mail