grrrr. I'm an academic (yes, I know, I know) and when I am on holiday or out of the country for some reason (e.g. when I am unable to access email during normal working hours) I use an out of office reply. It's a week until term begins and every bloomin' colleague I try and email (to finalise details of timetabling, rooms, training days etc etc) immediately pings back an 'out of office' reply with no end date stated!!
I think this is a bit much - I don't expect people to be tied to email (which is hardly good time management) - but it would be good to know that they are around and that I might expect a reply within the next decade??