NOTE: If this is for a shared mailbox, use the web outlook, click your picture in the top right and then click open another mailbox and type in the email address you have access to.
On the View tab, select the Settings gear View settings in new Outlook or on the web click the Setting gear in the top right.
Select Accounts > Automatic Replies.
Select the Turn on automatic replies toggle.
Select Send replies only during a time period, and then enter start and end times.
Under Send automatic replies inside your organization, enter the message to send while you're away. (You can use the formatting options for text alignment, color, and emphasis.)
To set up automatic replies to other people, select Send replies outside your organization, then add a separate message for that audience.
Note: Sending replies outside your organization will send your automatic reply to every email you receive, including newsletters, advertisements, and potentially, junk email. If you want to send automatic replies to those outside your organization, we recommend choosing Send replies only to contacts.
When you're done, select Save.