This topic shows you how to use the Automatic Replies tab. Use automatic replies whenever you want to let people who send you email know that you won't be responding to their messages right away. After automatic replies are turned on, they'll be sent once to each sender.
To turn on or modify automatic replies, do the following:
Open Outlook on the web and login to your account.
At the top of the page, select Outlook (or Mail).
Note The setting is also located in the Outlook on the web options. At the top of the page, select Settings > Options. Expand MAIL | Automatic replies.
For further information, click here to access the Microsoft Outlook How To guide.