Add an Autoresponder Email Message
Autoresponder messages are a great way to keep people up to date of your absence. They are easy to setup.
(1) Go to your webmail account and click your email address (top right of the page), then hover over and click 'Autoresponders'
(2) Now click 'Add Autoresponder'
(3) Fill in as per instructions on-screen
Last of all, click 'Create/Modify'