If you will not be checking your email for a while, you can create a reply that will automatically be sent to people the first message time they send you an email while you are away.
There are two ways to activate the "Out of Office Assistant," either from your desktop Outlook client or through Outlook Web App (OWA). Note that Mac users must always use OWA to activate the Out of Office Assistant.
From your desktop Outlook Client
From the Tools menu and select Out of Office Assistant.
Activate the Out of Office assistant,
check the button, "Send Out of Office auto-replies"
check the button, "Only send during this time range:"
enter the start time and end time
type in an auto-reply for senders inside your organization
click on the tab, "Outside My Organization"
check the button(s) to choose whether to send this reply to your Contacts only or anyone outside your organization
type in an auto-reply for senders outside your organization