An auto reply rule is used to send an automatic reply when you receive items. By default, you only reply once per user so users don’t get repeated messages from you, but the rule can be configured to reply to every item that you receive.
Click Tools > Rules, and then click New.
Type a name in the Rule name field, such as Auto Reply.
In the When event is section, make sure New Item is select and check Received.
If you want to reply to all items, leave the conditions the way the are or specify the conditions that you want to use to filter the items.
IMPORTANT:If you want to reply to all items and not just once per user, select Define Conditions, and have it set to Subject [] * End. This means Subject contains anything. This needs to be set in its own group if you have more conditions set. This lets the rule reply more than once per user.
Click Add Action > Reply and specify your reply setting and any other actions you want on the item and then save the rule.