In your Outlook mailbox, click on the tab File (upper right corner) and on Automatic Replies.
Select Send automatic replies. If you check Only send during this range, your automatic replies will only be activated during a preset time.
You will need to write your message in the tab Inside My Organization, that is mandatory. If you would like people outside your company to receive a message when they send you an email, you will need to fill the Outside My Organization (On) tab also.
If you have any problems, please contact firstname.lastname@example.org.