exchange in mail-how to stop all hotmail emails downloading iPhone

,I wonder if anyone can advise. I have active sync set up on iphone 4 and it works perfectly! The only problem being is that it downloads all messages since I set it up despite having set the settings in general account options on the iphone to show 25 messages and the exchange account is set to sync 1 day
is there any way of just having a days emails sat on my iphone as I do with gmail as I now have 160 emails in my exchange account on the iphone. If I delete any , of course I lose them from the server!
Help!!! with thanks
macbook pro Mac OS X (10.6)