1. Click Tools located on the main toolbar.
2. Click Out of Office Assistant.
3. Click I am Currently Out of the Office and enter the text you want to appear when
    someone emails you while you are away from your office in the upper box area.
4. Click Ok.

Make sure you turn this off after you have returned to your office. You would follow the same process but click the option I am Currently in the Office.

If using the webmail to complete this task:
1. Click Options located in the lower left corner – it looks like a sheet of paper with two
    punched holes.
2. Click on I am Currently Out of the Office and enter the text you would like people to
    receive.
3. Click Save and Close.