I am using Windows Mail and, having downloaded all my emails yesterday, on downloading today's messages, I find that all of yesterday's are received again! I have ensured that "Leave a copy of messages on Server" is unchecked, but what else do I need to do?
Thanks for the thought. I have phoned Orange - at an extortionate cost - and they reckon that there is no problem at their end. It never happened when I was using OE, but having just switched to Vista, I am now using Windows Mail, but it is not that different from OE.