Follow the steps below to set an out of office reply in OWA
2. Select Set Automatic Replies from the drop-down menu.
3. Select Send automatic replies.
4. If desired, select the Send Replies only during this time period check box to schedule when your out of office replies are active. If you do not specify a start and end time, auto-replies will be sent until you select the Don't send automatic replies check box. NOTE: Previously used automatic replies associated with your email account may appear in the text boxes for your use, if desired.
5. For replies to senders inside your organization, type the response that you want to send to colleagues while you are out of the office. They will receive the notification only once.
6. For replies to senders outside your organization, select Send automatic reply messages to senders outside my organization check box. Select whether you want Send replies only to senders in my Contacts list or Send replies to all external senders. Type the response that you want to send while you are out of the office. They will receive the notification only once.
7. Click Save