Snow Leopard Mac Mail & Exchange 2003

[dzuroff]

I am having a heck of a time getting Mail in Snow Leopard to work with Exchange 2003. Since Mail natively supports Exchange 2007 I have to use IMAP to connect to Exchange 2003. The problem I have is when Mail is running and communicating with Exchange it slows the server down to a point where it affects all other users connecting to Exchange. It causes long delays and Outlook displays a message stating it lost connection to Exchange and is waiting for a connection. If the user running Mac Mail closes Mail then the server is back to normal. I have seen other references to this in various forums however I am unable to find a fix. I tried configuring Mail to connect directly to Exchange via IMAP, and I have also tried using DavMail as a local mail gateway however Exchange slows down in both scenarios. What can I do?? The Mac user really wants to use Mail however I am close to the point of telling him it is not possible with Exchange 2003.