Open Outlook
Click File
Click Automatic Replies
Select Send automatic replies
Choose Only send during this time range if needed
Set the start and end time if needed
Type your auto-reply message in the Inside My Organization tab
Type your external auto-reply message in the Outside My Organization tab if needed
Click OK
Open Outlook on the web
Click Settings
Click View all Outlook settings
Click Mail
Click Automatic replies
Turn on Automatic replies
Set the time range if needed
Enter your message
Click Save