We too use Exchange server 2003 SP1. We have not upgraded to SP2 for various reasons (including the fact that we tried to install the original IMF after SP1 and it just hosed up our system on 3 install attempts- thought that SP2 with integrated IMF would do the same). The problem with the CDO patch for SP1 is that Microsoft will not support if there are problems (I was told yesterday by the folks at Microsoft support that they don't support SP1 any longer-even though they put out a patch for it). So if you install the CDO patch for SP1 and it messes up your Exchange server (it womped my OWA on a test server), Microsoft will not help you. I wish that a third party vendor would quickly enter this fray and offer a decent, reliable solution.