I don’t know what happened, my out look deletes all old emails (older than 6 days), even they are kept on my local drive in *.PST folder, they are even deleted from this folder. I do not know why. 6 days is the time, emails are left on the server.
So far I tried going to Tools -> Options menu and going to the last tab (other tab), then selecting Auto Archive. Here i disabled, “run auto archive every 14 days”. I hope this will help.