Setting an out of office reply in Outlook

In new Outlook click the gear > Accounts > Automatic replies. Turn it on, tick the box to send replies only during a time period and put Friday to your return date, then tick Send replies outside your organisation and choose anyone rather than contacts only. Two message boxes, one internal, one external. The dates mean you don't have to remember to switch it off. Classic Outlook is File > Automatic Replies, with an Outside My Organization tab.