There are two ways to set up an Out of Office Automatic Reply when using Office 365. You can use Outlook, or the Outlook Web App.
Set up an Out of Office reply via Outlook Application
Open Outlook
Click File
Click Automatic Replies
Enter your Automatic Reply message
You can configure different automatic replies for senders inside or outside the organisation. You can also choose to send Automatic Replies indefinitely, or during a specific time frame.
Set up an Out of Office reply via Outlook Web Application
You can configure different automatic replies for senders inside or outside the organisation. You can also choose to send Automatic Replies indefinitely, or during a specific time frame.