Open Outlook
Click File
Select Automatic Replies (Out of Office)
Select Send automatic replies
Choose Only send during this time range (optional)
Set the Start time and End time (optional)
In the Inside My Organization tab, enter your out-of-office message
In the Outside My Organization tab, select Auto-reply to people outside my organization (optional)
Enter your external out-of-office message (optional)
Click OK to save and enable the out-of-office message
To turn it off, return to File > Automatic Replies (Out of Office)
Clear Send automatic replies
Click OK