Outlook Connector is currently under development by a friend of mine... He recently got some corporation sponsorship so hopefully it will be completed soon...
BUT IT'S PURPOSE IS TO EXACTLY SOLVE THIS PROBLEM.

It connects into Outlook (via the Mapi protocol) and allows you to bypass an exchange server and instead use an open source linux solution. it is already in beta on sourceforge.net...

SO IF ANY OF YOU WANT TO HELP... I AM SURE MY FRIEND WOULD APPRECIATE IT!!!